Probably for the same reasons people hit a plateau when pumping iron. See also [plateau effect](https://en.wikipedia.org/wiki/Plateau_effect).
Talking about ratings. I think they plateau because they dont have depth and width. Check this site out, which helps you look up all profiles at once and even get a GMFISH score or simply copy paste tournament listing and get all their USCF and FIDE ratings at once. It even gives you the live USCF rating. https://gmfishrating.com
Discover the reason of your plateau this way: Use the analysis board with the database focused on your name.
Start with your name as white, pick the top most popular move you played. Then press your name to alternate to the black database and repeat the prior steps (alternating colours) until you have no more moves to play. Put it in a study and get a server analysis of it.
My most popular opening favoured white and has a plateau of 8 ply.
My chess insights never said this was my most popular opening.
White: 16 Average centipawn loss, 94% Accuracy
Black: 25 Average centipawn loss, 90% Accuracy
[ECO "B30"]
[Opening "Sicilian Defense: Old Sicilian"]
[UTCDate "2026.10.27"]
[UTCTime "14:33:40"]
1. e4 { [%eval 0.18] } 1... c5 { [%eval 0.32] } 2. Nf3 { [%eval 0.2] } 2... Nc6 { [%eval 0.3] } 3. c3 { [%eval 0.0] } 3... e5 { [%eval 0.37] } 4. Bb5 { [%eval 0.16] } 4... Nge7 { [%eval 0.55] } *
Tiny centipawn losses caused by popular bad habits prevents us from progressing.
I think a player's strength is directly correlated to how strong their tactical vision is. But there's a problem with the way we study tactics. A typical tactics puzzle has you find the winning line in a position where the tactic already exists. That means studying tactics this way won't keep you from blundering yourself. So tactics puzzles only train half the problem.
I built my own tactics trainer to solve this very problem. It gives you two types of puzzles. In the first type, you have to make a move and avoid blundering.
The second type is a normal tactics puzzle like you'd find on any of these websites. I gamified it a little bit and added monsters and whatnot. It's totally free and I'm still working on it, so I'd love some feedback if you try it. https://beginnerchessprinciples.com/blunderer
"... going from good at tactics to great at tactics ... doesn't translate into much greater strength. ... You need a relatively good memory to reach average strength. But a much better memory isn't going to make you a master. ... there's a powerful law of diminishing returns in chess calculation, ... Your rating may have been steadily rising when suddenly it stops. ... One explanation for the wall is that most players got to where they are by learning how to not lose. ... Mastering chess ... requires a new set of skills and traits. ... Many of these attributes are kinds of know-how, such as understanding when to change the pawn structure or what a positionally won game looks like and how to deal with it. Some are habits, like always looking for targets. Others are refined senses, like recognizing a critical middlegame moment or feeling when time is on your side and when it isn't. ..." - What It Takes to Become a Chess Master (2012) by GM Andrew Soltis
https://web.archive.org/web/20140708093409/http://www.chesscafe.com/text/review857.pdf