For me, avoiding heap, or rather avoiding gc came when I was working (at work) on backend and web server using Java, and there was default rule for our code that if gc takes more than 1% (I don't remember the exact value) then the server gets restarted.

Coming (back then) from C/C++ gamedev - I was puzzled, then I understood the mantra - it's better for the process to die fast, instead of being pegged by GC and not answering to the client.

Then we started looking what made it use GC so much.

I guess it might be similar to Go - in the past I've seen some projects using a "baloon" - to circumvent Go's GC heuristic - e.g. if you blow this dummy baloon that takes half of your memory GC might not kick so much... Something like this... Then again obviously bad solution long term