Versus AI is the place to learn and teach, IMHO, also “try-mode” could help a little bit with that for the very basics.
QM may not be a “serious” place, so to speak, but people in there still try to win, there is still an actual match going on against another group of people, and in that sense is competitive already as far as the definition goes, even if that match doesn’t represents nothing more than the sole pursue of victory itself, no rank, no real reward, no nothing, just the joy of winning, but that’s all it’s needed for people to care about it.
Also, many people simply don’t play ranked or unranked 'cause they simply don’t like drafting, where they can’t always choose and play the hero or role they like any time they like, without having to wait several minutes for a match to be found, nor be “forced”, so to speak, to play another certain hero or role they dislike neither. QM may be a relaxed competition, but is an actual competition in the end.
So, unless you think losing is cool (or better said, making others lose, giving 0 ducks about them), then QM is not a place to learn, is a good place for practice, though, but learning and practicing are different things. In the later you at least already understand what’s going on and how stuff should work and how it should be done, you only need to get good at it. The former not only almost guarantees a lose for the team, but can be perfectly done without disturbing anyone in vs AI, where it belongs.