Completely not my experience:

I have lots of Signal contacts I cannot phone, since the phone number is never shared by default. Not even the signal contact is shareable. It is way too privacy focused to work easily.

i.e. I cannot even match two people I have in contacts unless one of them sends me their hidden username. Then they can talk to one another.

And people in my contacts don't use their full name. In groups, they often share the first name, making it confusing as hell. And many use an arbitrary nickname, most often the abbreviated first name I think but sometimes truly random stuff, and might even change that yearly with no mapping in my history to tell me who they were.

Keep an eye on Whitenoise. It's basically taken the technology behind Signal and placed it atop Nostr, so rather than signing up with a phone number, you do it with an npub (pubkey). Still in very early days so the features aren't all there yet, and battery use could be better, but they've got the basics of it working already.

"but overall there are better solutions."

Can you please name some?

Why the downvotes? A messaging app that requires a personally identifiable token is inherently not good for privacy…