[gotodengo]

At this point it's a backwards compatibility issue. Like you say for Ohm they now recommend using the omega symbol[1] but there's still code out there using the Ohm symbol.

Solving that wouldn't have helped in the Spotify case though since there's a ton of other edge cases like combining characters 'e' + ' ́' vs precomposed characters 'é' which still cause the need for an idempotent canonicalization of usernames.

Not to get too far from the topic at hand, but I came across the Spotify article earlier this week while looking to support Unicode usernames in an application. After consideration I've decided to just lock things down to ASCII for now. It's just too big a case to consider and there are bigger fish to fry.

[1] https://en.wikipedia.org/wiki/Ohm#Ohm_symbol