They handle a lot of sales [1], I do not think they can be called irrelevant under any reasonable definition of the word:

> In the past year alone, [customers] spent $208 million on 14.6 million digital albums, 11.2 million tracks, 1.55 million vinyl records, 800,000 CDs, 250,000 cassettes, and 50,000 t-shirts.

[1] https://bandcamp.com/about