That it could make more money by making small adjustments to the overall game.
simply putting out the achievements for free or always buyable with BE, even the unique ones like rune pages are right now, would have players have a sense of progression and would help them feel like they actually did something,
this would bring in more players and give them a longer lifespan in the game, encouraging them to main more champions.
Tweaking the grade system to stating more clearly how to get a specific grade by having more than such CS or vision at a given time specifying the values for every champion, as different champions may have different requirements based on their role and farming capability, basically removing the "you are compared with the average of players that use that champ in that role" as you would be compared to a static value instead of a fluctuating one, reducing the impact smurfs have to the game in the process (smurfs going against inexperienced players end up with higher than average scores that end up tainting the average you are compared to). Also, keep in mind this wouldn't make anything easier, just more fair, since there is a big difference between knowing what to do and actually pulling it off in game.
another thing to do would be to swap vision and CS importance in games, not only you would have players learn how to ward properly but you would lessen the players who steal jungle camps (laners) or lane minions (junglers) because they need a certain grade.
this would relieve the stress you get from carrying a game, having a perfect KDA, good CS and vision and still getting an A+, resulting in more relaxed players and less flaming in games.
Removing the limitation to chests so you can earn all your chests with the same champion, since it has no real reason to be there while still keeping the 1 chest per week limitation with 4 maximum winnable chests.
This, paired with the grade system, would make players less stressed and less prone to tilting AND would make players who want to earn free loot more skilled with their main instead of dropping them for weeks to win the free chests with another champion they aren't that familiar with. This wouldn't impact Riot negatively as the 1 chest per week limitation would still be in place and you would still need a key to open them.
Yes, all these boil down to "giving free stuff" but it's free stuff riot is already giving out, this would just make them more clear and make players less stressed about getting what they think they earned.