Yes, most of us learn to sing 'by ear' even if we learn to play 'from the dots'.
I'm hoping that just as my ability to play by ear has improved after several years of going to sessions, my singing from the dots will now I'm in a choir. But for now YouTube, Choirparts etc are my crutch. It doesn't help when the music is in a stupid number of flats. When learning piano we had to sing different intervals for some of the grade exams, but to turn 8 flats into tonic-so-fa then work out what the intervals sound like would be worse than a 5 yr old spelling out c-a-t with a finger under the page. Far too slow.

(I didn't realise I was logged out when I posted on 22nd)