In PHP the new code will be loaded in an isolated process instead of being system wide, and you will not be able to redefine a module/class that already exists. This is best to try to run malicious code.
Plus PHP is easier with “one click install” providers I guess. That being said, I find using Luerl for plugins could be very cool and safe, though maybe not very fast.
Thank you for all your responses, it boosted my confidence.
I thought I will list some of the top Wordpress plugins & find-out how to implement it, likely the most of them should be implemented in core, including:
w_1200, w_1200,h_800 ), if it slow, we can make them communicate via RabbitMQAm I missing something important here? 
Thank you for reading;
I’ve spent some time thinking about this and some time going down paths I abandoned.
I have an effort underway which I’ve shared some stuff about in my newsletter. Since I’m aware that a CMS is a massive effort I’m trying to start with foundational libraries and stacking those bricks up over time.
Even on just this forum I’ve seen this idea come up and fall down.
I think Elixir could do great at CMS things but the road to featureful enough is absurd.
Give it a shot if you like. I applaud any effort in that direction but be aware that it is a lot of work.
My view on “solving” the CMS problem is pretty particular and it involves tackling this particular painpoint, among others: Underjord | The WordPress merging problem
For me it begins with making content type creation strong. And going down that route you’ll find out that Ecto schemas really are very compile-time and if you don’t want arbitrary atom proliferation, from code-gen, as a risk that leads to other choices. Can of worms 
I can share more when and if it starts to make sense
There is a CMS system in itself for many years: Zotonic
However, Zotonic is based on Erlang, which can be extended and customized with your own modules and templates. The template-system is based on erlydtl.
My interest is rather Ecommerce, also for this Elixir would be actually well suited, there are also some companies that use it exactly for this, but just proprietary:
https://www.stitched.co.uk
https://www.therealreal.com/
For an open source ecommerce system you would need the possibility to develop plugins, especially to program your own themes for the store.
In Zotonic, for example, you can extend the template’s in a simple way via the blocks as in Django or PHP-Twig.
From time to time I try to figure out how to do this in Phoenix, but unfortunately I haven’t made any progress. Especially if there are other solutions instead of blocks? In such a store system, however, there can be hundreds of blocks, which are very fine-granular (as you can see in the shopware example).
I would be grateful for ideas regarding extensible templates in a nice way.
OMG I would so help you do this!! But I have to come back when I’m more awake. I’m going on awake idk, something crazy like 24+ hrs now. Yea so, goin to bed soon. But I love this thread. I’ll be back!! WOOT WOOT I’m already excited to do this!!!
I agree. The 3 complicated issues in building a decent CMS are:
When you say, Wordpress, what do you mean, a content management system with WYSIWYG editing, image storage, and installable themes?
I would say those 3 are features that are not core to a CMS. Some CMS are headless, hence don’t need themes. If by WYSIWYG you mean drag and drop page builder, there were CMS before this exists. Images is just a type of content usually called Assets. Most CMS include a Digital Asset Management module, but, again, it’s an added feature.
I would venture the minimum set of features of a CMS would be:
then, there need to be a way to distribute that content, depending on the platform. On the web, it would be linking a URL to a piece of content.
I’m intrigued by the title of the post since it’s something I’ve been thinking about a lot, I see the following problem, coming from the place of wanting to sometimes build websites for individuals and small to medium scale institutions:
Wordpress and similar PHP-backed headful (also rendering the website) CMS systems still offer an unmatched workflow for some reason:
Now web development has progressed over time, and there are much better options for building content-driven websites, I really like static site generators, Astro is a great one for example, I think the developer experience is kind of unmatched and on a technical level, generating HTML ahead of time and then just serving it makes a lot of sense compared to rendering every page on demand and hitting a database on every request when the content really only changes like once a month.
The problem is there is no CMS with a workflow as straightforward as what I mentioned above.
If it’s your own website, editing markdown files by hand may be an option, but you can’t expect non-technical users to be doing that, it barely works even with a wysiwyg editor.
There is the option of using a headless CMS, the cloud / Saas ones are usually quite expensive (see: Contentful), self hosting an Open Source one (Payload, Strapi, Directus) is feasible but comes with a maintenance burden – then you also need to rebuild the page on every change so you’d have to set that up usually on a secondary service that does the building and hosting like Cloudflare Pages or Netlify, which also means you probably also want to have a hosted git repo connected to that, from a third service like GitHub or GitLab, it just explodes in complexity, and how do I hand some amalgamation of services like that over to a client?
The git-backed static CMS (Like Netlify CMS, now Decap) options are okay, until you are dealing with sites that are heavy in media, then storing everything in a git repo is not feasible anymore and you have to add on services like a git LFS provider or S3, and you always need a minimal backend for authentication anyways.
My point is: I would love something that replaces Wordpress in simplicity for building completely custom content-backed websites for third parties that are not massive companies, I feel like there is nothing targeting that niche at the moment.
I’d prefer something that works with one of the existing excellent SSG solutions that there are, Astro is the one that comes to mind, the missing piece for me that I’ve seen no other CMS (except maybe Publii) do is actually doing the site builds on content change rather than giving you a webhook and pushing you towards setting that up with an additional third party service.
I think BeaconCMS by Dockyard is trying to solve this .
They are targeting the features you outlined which makes Word Press popular
including re-usable UI components and drag and drop UI page builder.