But the idea that something you did in five minutes is going to be better than heroku (in all ways?) is.... I don't know what the adjective is. Heroku is very mature and polished software, that almost always does what you expect -- it's a very non-leaky abstraction, I guess. You can almost always get away with ignoring the details. (Yes, not 100%, but almost always). And there's pretty high quality documentation explaining how all the parts work, when you do need to figure out something.
This is unlikely to be a "better heroku", that solves all the problems heroku solves with as little time/energy from the customer -- if it really is, this post definitely didn't convince me of it, I still don't totally understand what it's even demo'ing. And it just makes gitlab look rude and/or desperate to have a heading that's simply "Do not use Heroku" -- because it's not open source, is the argument, i guess? Plus a vague and sarcastic tweet? How would we feel if heroku (or github) had an article titled "Do not use gitlab" with no more of an argument than that? It's just... childish.