He clearly proved that he wasn’t ready to be a master - it’s not like a martial arts rank that you mostly just get because you’re skilled, they also want you to be able to embody the ideals they stand for (flawed as they may be).
They certainly could have trained him better, but that makes them idiots, not assholes. But first and foremost, their most important failure was not detecting that Palpatine was a sith.
Mundi had a special exemption because his species was going extinct, and it was always supposed to be about attachment anyway - it’s plausible that Mundi was able to produce offspring without personal attachment. Anakin could never have done it like that.
No.
Most of the issues with video games come from either game-related social media (e.g. bullying, political indoctrination, or just the massive time sink that MMOs and other multiplayer games can be which has an element of peer pressure) or stuff that is relatively easy to police on a per-game-basis (e.g. gambling, extreme contents). You can certainly waste a lot of time with single player games, too, but at that point we might as well not allow children to go home from school at all.