indie may have been used to describe certain types of music, but wrongly. indie was short for independent, and didn't describe a type of music at all. all sorts of music were indie
why would it feel wrong to dismiss an album from being considered an indie album if it wasn't an indie album because it was on a major label? what difference does it make?
you may as well ask what's the best rock album and let people pick albums by herbie hancock and kylie. it just defeats the whole purpose of asking such a question. albums like ok computer and a different class were on major labels so benefitted from a specific type of distribution and promotion that most true indie records didn't have. a good chunk of records mentioned are really britpop records on major labels, not indie
I would agree that the term 'indie music' generally refers to indie labels. And indie (or true indie labels as you say) is best defined by the label carrying out all the production processes; signing artists, recording, publishing, distributing and marketing their works. Some indie labels signed contracts with majors for distribution! So presumably they don't count?
But Indie rock and indie pop are equally legitimate terms referring to a type of music usually but not exclusively associated with artists on indie labels.
The question actually was what was the best 90s indie music album? The indie bit simply limits the number of albums we can choose from. More interesting than the semantics is why people think their particular choice is the best.
Again. I picked Slint's 'Spiderland' because of it's musical innovation, it's use of complex rhythms, atmospheric sounds, its poetics, imagery and it's influence on other artists (Mogwai, Explosions in the sky). Musically, I would describe it as indie rock and/or post-rock, I don't believe genres are rigid categories. I only wish I had heard it when it came out, it was some years later.