"I never used a capo a day in my life!" ... There's time yet...

You can use a capo for three reasons - one is because you need to play a tune in a key you can't cope with. And there are quite a few of those. G# for example, on a standard tuned guitar. (And I'm sure that you are a lot better at those kinds of keys than I ever will be.)

Another reason is that yiu have learned an accomoaniment in one key, but on the night your voice wants to sing in a different key, and if you have to coincentrate on playing a different accomopaniment it'll take attention away from the song, which is the thing that really matters more than any accompaniment.

And the third reason is that even when you are quite able to play in a key, and even if you're good enough to do iy at a moment's notice without being distracted from the song, the accompaniment you want will sound better with a capo and a different pattern of chords.

I'll often be singing a song in C, but with the capo up on the 5th fret, so I'm playing as if it was in G. That's not because I can't play in C!

But what is a mistake is when someone wants to play a particular accompaniment, but they won't use a capo, and they have to force their voice to sing in a strained and unnatural key. (And I'm thinking of people I've known in singarounds and such.) The song comes first.

Incidentally, Segovia was known to use a capo.