Acts that came to prominence when their members were in their 30s or 40s?

So if a guy has to pretend that among other things he's 10 years older than he really is, does it prove that there's an 'uncool dad/mom' period for musicians roughly between the ages of 35-50 where they stop being taken seriously and just have to ride it out until they're pension-age and can cast themselves as roguish elder states-people? I'm thinking about the big-hitters of my youth - people like Damon Albarn and Stephen Malkmus whose cred seems to be at an all-time low at the moment, but I'm sure will bounce back in about 10 years' time.

would that be the Albarn with a music group that has a new tour coming up

I don't think anyone has to pretend they're older necessarily it's just:
- studio guy wishes he could get back to the basics
- Jack White, bunch of other acts make blues riffs and back-to-basics production cool
- guy adds a decade to his age to make it seem like he was an unknown, broke contemporary of people from the age people in younger acts think were cool
- profit!

it's easier to add years than remove them from your age typically, although people do the latter all the time

I think there are probably more acts coming to prominence in their 30s than we think of, mostly because of the age deflation that goes on.

Sia's entire public image is more of an artistic statement but at least a small part of her incognito act is due to her not wanting to put her face/age/etc out as the defining characteristic of her music

I just learned Sturgill Simpson is 41 and was in his mid 30s when Metamodern came out

The B-52s. I was surprised to learn (in this Pitchfork piece) that Kate Pierson was born in 1948, had been a full-on hippie, etc. (Though the other band members are older; Fred Schneider seems to be second-oldest surviving member, born in 1951). So some of them were just scraping 30 when they formed the band, and Pierson & Schneider were both around 40 (give or take a few years) when Cosmic Thing broke big.

*though the other band members are younger...

Debbie Harry was 36 when "Rapture" came out