I should clarify. Yes, scaling champs should be fully built by the 22 minute mark, but as stated, the vast majority of games don't even reach the 22 minute mark. I don't have any data so I could be wrong, but it seems like due to the faster paced nature of wild rift compared to pc, end game scaling champions and runes are already under picked/used. The meta damage rune is brutal over gathering storm because early game and snowballing is more reliable then praying to reach the end game that won't always happen. Not to mention wr players quit way to early thinking a game is decided after the first objective. Gathering storm for example, gets really useful after the 25 minute mark but that's a small fraction of games and even less so with self destruct towers.
This change would further discourage players from picking late game scaling character and runes. Burtal will be used even more.
The benefit to me does not outweigh the cons. Games are faster, but a whole style of champions will be indirectly nerfed and players will likely to use those champs, runes, builds even less.
Additionally, this doesn't seem to be a well received change (for ranked players). It seems like the majority who are in favor of this change are the more casual players with limited time. That is why I see this being good for standard.
Standard and ranked modes are already different: the same champion can be both on your team and the enemy team in standard, there is a banning system in ranked, and match making is (seemingly) much more loose in standard.