I think Riot's issue is they're trying to pander to both types of casual players

There are two types of casual players. There are the actual casuals, the ones that play the game at a low level and don't really play the game enough to make sufficient strides in ranked gameplay

and then there are the consumers. The people that don't play but constantly digest the content. They're the stream watchers, content creators, LCS fans, cosplayers, etc.

The problem? Both want to see the game go in completely separate directions, and Riot trying to do just that. You know how you always hear, "Riot is just balancing for LC$"? How do you think high elo players feel when they open up their client and see Garen and Yorick and Yi nerfs? Same with the constant calls for Draktharr to be nerfed when it sees marginally less pro play than any other type of build.

I will say though there are some points where gameplay is right; they do cater to LCS, The mana nerfs, for an example, were to gate people who were particularly competent with mages champions and it sucks for low elo players who have difficulty managing mana. Also, the AD buffs that pushed them back into being dominant picks when they were finally getting picked with the same frequency as picks like Heimerdinger and Swain.

And so Riot is essentially doing the splits trying to appeal to an audience that wants a slower paced game with more mechanics that are not only forgiving, they outright nullify aggressive strategies, and an audience that wants games that are fun and digestible instead of slow paced slugfests.

This leads to high elo gameplay being almost entirely neglected, and it sucks. Some LCS strategies aren't translatable to solo queue, but almost every bit of content that works in high elo works in low elo if you're proficient enough at it. Every champ, every item that's good, etc. So when balance for high elos is neglected, and the only things that get nerfed for low elos are outlier champions that didn't deserve to get touched anyway, it causes this sort of rotting in low elo where the game tends to suck and it's just unclear why.

For example, let's take the jungle. If you look through my last couple of points, it's fairly obvious I hate the jungle. The reason being in high elo far too much focus has gone to whether or not the jungle can 1v5 the game. And I get that in low elo, or if you're playing a tank, the jungle probably feels really bad to play because a lot of it is built on pathing (which, if you're low elo, is not a strong suit of the junglers). But when you get a jungler playing Graves/Camille/Eve/Taliyah/Xin Zhao, and he knows how to path, the game might feel overwhelming and unfun. Graves will pop out with a kill or two and his Warrior Stormrazor and say, "Bend over I need the LP".

So what happens if jungle gets nerfed? Let's say, hypothetically, junglers get their income lowered. How does this affect low elo? Picks and Compositions - You don't want carries in the jungle if they're not earning gold. You instead opt for tanks. Damage Creep - I don't think damage creep is honestly as prevalent as people say. I think it's maybe 10-20% damage sources and 80-90% picks. If everyone picks squishy, high damage champions, everyone dies much more quickly due to the low resists and their opponents' overall absurdly high damage values. Even if you're playing a tank, you're going to die more quickly to 5 damage sources than 4, especially if all of them have penetration in their core builds. If 2 or more players opt for tanks instead, that's one person on the enemy team that will take significantly longer to kill you and one person on your team that will take significantly longer to die. Game Pace - Unsurprisingly, game pace slows down. Fights take longer. It's less effective to run assassins or bruisers so you could likely see some mages who can't reach the backline to burst squishies. They end up focusing the tanks instead and so it becomes a less bursty game even though you haven't touched anything beside a single role's income.

So with changing very little to help high elo players, it can have a significant impact on the game that could quite easily push it to be more of what boards and generally casual players think the game should be.

And it really sucks that high elo players get neglected on a lot of these issues. We're often the ones putting the most effort into playing and learning the game and to have our version of the game in a state of decay because we want to appeal to a casual fanbase pushes away the fans you'd normally consider the most loyal.

It was really nice when Hashinshin's requests were taken personally, and Riot worked to bring fighters back into the meta, but there have been a number of issues since then that haven't been touched on. I've yet to see Riot do anything in the way of working on Doublelift's video. I don't see any changes to dominant picks, compositions, and strategies that have been proven to define the meta for months now, and I've been waiting a long time to see some followup. I feel like other high elo players feel the same.

tl;dr I don't think any form of creep is the issue so much as a state of negligence for the most dedicated and skilled players. If Riot returns to focusing on high elo gameplay more personally, they can make small changes that trickle down to the majority of players and are actually applicable to them. High elos don't play things that are miles better than anything else. They play things that are better in 51 out of 100 cases. All you have to do is turn that down to 49 and suddenly, teamcomps shift dramatically. The game's meta changes and without actually meaningfully changing the game itself the playerbase changes how the game is supposed to be played. I think that's how Riot will find success in making the game more enjoyable and in making the game more enjoyable they'll find it's a lot more profitable and long lasting.