Unpopular opinion: riot told you how to get chests, just play other champions and do well on them
you should be playing multiple different champions to get a better understanding of the game anyway, but that's just my opinion.
It's not that hard. They gave clear and defined objectives. Meeting those objectives gets you chests. Riot shouldn't have to cater to a minority in the playerbase just because they don't like the rule set given to them and don't want to go out of their comfort zone.