I don't find that reasonable at all. Why would a game incentivize 'doing dailies', as opposed to 'play a lot, get a lot'? Going from 2-5, I would just log in for a daily ARAM, and I hit honor 5 the same day as a friend who plays 5-10 a day. From honor levels, to keys, to capsules, it's all built on casual play.
A limit of 12 fragments is already bad enough, but having capsules use key fragment slots makes it even worse, especially if the capsules have a high rate of bricking. If some dude wants to play League 18 hours a day, and maintains his honor while doing it, he should get more rewards than the guy playing 1 game a day.
It's a lot harder to stay untilted for 300 games than it is for 30, and if enough hardcore players are staying positive over hundreds and thousands of games, it will have a much larger influence on the community. Honor rewards should actually get better the more you play and stay positive, but it doesn't benefit anyone to do that.
Putting limits on player rewards for playing a game is some archaic shit, and should have died off a long time ago. No company should ever offer a system that is "okay dailies done, rewards received, time to do something else". There are so many games and genres now, that our choices are unlimited. Give me rewards for playing more, and permanently unlock that fucking vault full of custom games that I'd rather be playing while you're at it.