They might be but you keep forgetting people want drop-in works-out-of-the-box tools and not an engineering PhD exam when working. 
If I am to embark on such an adventure I’ll make doubly and triply sure that the experience is near-seamless, easy and quick. I have no intention of introducing a spaghetti monster that makes people’s lives harder. If that were to ever happen I’ll just freeze the GitHub repo and put a huge banner on it: “WARNING! DO NOT USE!”.
Not sure I agree with your opinion on umbrellas though – or with anybody who opposes them really. Umbrellas, much like the proposed future private functions, are a communication-of-intent mechanisms and a way to separate bunch of source files from each other. Nobody claims they are magic. If you have this dependency graph: business_logic >> business_data >> data_app_using_postgresql then no technology in the world can stop a dedicated programmer from cutting out the middleman and thus not respect semantic boundaries.
Example from almost the start of my career: people have been known to reverse-engineer compiled C++ multiple-inheritance classes which were specially crafted to hide the implementation – and they did so quite successfully. What can you do? If they don’t get the message of “here be dragons, don’t touch” then let them tinker. But I ain’t ever accepting a single “bug report” from such people.
So to this day I can’t understand the objections against umbrellas. They simply give a small peace of mind and address a part of the single-responsibility-principe / separation-of-concerns patterns. Nobody says they do something more.
