> But apparently not enough time to become even a half-decent player, since I never broke through the 3800 MMR ceiling in Dota 2.

Eh? 3.6k is Legend[5] which is 83rd percentile. https://www.opendota.com/distributions/ranks Maybe it didn't feel like it in an evenly matched pub, but objectively speaking you were very good.

But be as it may, I'm happy you've found hobbies you enjoy more.