Mutemath.
Drummer Darren King (an amazing drummer btw) abruptly quit the band for good in the middle of a tour one year, and while they did find a replacement for him to finish out the tour, that was the thing that started the unraveling of the band. It wasn’t long before all the remaining members left, leaving the founder and lead singer, Paul Meany, alone with the name. He’s tried to do some small things with it since that time, but he admits (as he should) that Mutemath’s real existence is in the past now.
IMO a full third of Mutemath’s essence was Darren King’s drumming. It made sense for the band to cease existing without him or someone like him. The replacement they used on the tour was ok but just not the right fit. He (seemingly) couldn’t do what Darren did.
In terms of song quality, even I as a fan can admit they were hit and miss. But I still loved their stuff overall and there was no denying the talent involved, ever.
Also, I’ve seen them in concert 4 times, which makes them my #2 artist on setlist.fm :)