There's a lot of misunderstanding here. The quality of LLM writing has not plateaued, it has dropped significantly. They've cut it to the point where people start noticing.

Do a search on "Claude Sonnet 4.5" on Reddit and you'll see lots of disappointed users [1]

If I could give out ratings,

Average human with a degree: 5/10

Sonnet/Opus 5: 2/10

GPT 6 Astra, 5.4 Sol: 3/10

Sonnet 4.6: 8/10

Claude Sonnet 4.5: 9/10

GPT 4o: 6/10

GPT 4.5: 10/10

GPT 3 Davinci (with a lot of coaching): 7/10

[1] https://www.reddit.com/r/claudexplorers/comments/1ta6f9c/i_s...