For use cases demanding the most intelligent model, yes they aren't.
However, there are cases that you just can't use best models due to latency. For example next edit prediction, and applying diffs [0] generated by the super intelligent model you decided to use. AFAIK, Cursor does use their own model for these, which is why you can't use Cursor without paying them $20/mo even if you bring your own Anthropic API key. Applying what Claude generated in Copilot is just so painfully slow to the point that I just don't want to use it.
If you tried Cursor early on, I recommend you update your prior now. Cursor had been redesigned about a year ago, and it is a completely different product compared to what they first released 2 years ago.
[0] We may not need a model to apply diff soon, as Aider leaderboard shows, recent models started to be able to generate perfect diff that actually applies.