I started learning guitar using tabs. It's good for easily picking up a song, but I found it painful to learn new songs. Everything I played I simply memorized and learning a new song was always a start from scratch.
I mostly play classical guitar and now force myself to get better at sight reading standard music notation. I find it extremely hard but very rewarding because I'm now able to simply pick up a sheet of music and with a couple of tries figure out the basics of a piece. It opens up a whole library of beautiful pieces.
I'm working on becoming a better piano player and forcing myself to read sheet music. To your point, it's incredibly difficult. To the point that I'm 50/50 about whether I'll ever get good enough for it to matter. I'm learning songs, but in nearly every case I'm mostly memorizing the song. It's really frustrating.
I've been advised to use a keyboard to record my playing without being able to hear it and playing straight from the sheet music. I haven't tried it yet though.
Same, I finally managed to stick with learning standard notation this year after several false starts and I’m kicking myself I didn’t start earlier. There were a few tough moments where it seemed like I’d never get (learning about key signatures, moving past 1st position) but now I’m starting to get comfortable playing up to the 7th position. It’s so nice being able to just buy a big book of Sor or Giuliani or Carcassi studies or even some Bach transcriptions and play them straight out of the book instead of needing to listen to a performance first and then look at the tab.