I don't understand, is people still using it?

Once Elonified and walled, was already a clear bye bye years ago.

why there would be still the need to have an account and post stuff there?

boycott is the answer.

loosing and having few users is the biggest pain, let them drain into the void.

I use Nitter/Xcancel entirely because I don't have an account, and Twitter is now unusable without one. There's still content of some value there. People still link to it and now I can't read what they shared with me.

that's what I believed and did too till now, but would be good to remove the problem completely finally.

Sad to see you getting downvotes for facts. What you stated is exactly what I witnessed myself.