Honestly? Personally I’m 
on this. This is more like how to make Erlang and Elixir compile - not a good way to prepare environment. In modern environments versions managers like asdf are used instead of doing everything by hand and they also allows to compile Erlang and Elixir - not even mentioning that there are up-to-date binary releases. Unfortunately your way you could scare new developers already at the Erlang step. 
The second thing you are doing wrong is not to use a tools your distribution provides. Yes, version managers like asdf does not handle dependencies by you, but their plugins have usually a simple one line command to install dependencies using apt and that’s more than enough for a new developer to know. 
What a guide like you could do is as said using all helpful stuff your distribution provides. I already gave an example about it here:
In Gentoo btw. it’s even simpler, because *.ebuild files are text files and you don’t have to generate a deb or any other files. 
The biggest problem with your guide however is how to do update your installed by hand environment. In very short people need to go all over again and ensure everything works which could be fully automated and the update then looks like:
- Install distribution updates (using apt for example)
- Install updates using version manager (using asdf for example)
and … that’s it! Story end. You have to spend only “5 min” only once and then you can the time you saved on more (or less) productive things. 
