What's with the "valley girl" accent I see so many (even non-white) women in finance talk with?

I've seen a lot of junior women bankers (white and non-white if they were born in the West, first-gen immigrants and internationals don't have this) talk with a sort of "valley girl" accent with drawn out words and a lot of changes in pitch/tone that doesn't come off as professional at all. I see this in my day to day workplace, while visiting my alma mater during recruiting cycles and on IG/TikTok whenever "day in the life of a girlie in finance" comes up. 

It's not professional at all and it makes me want to stick a knife in my ear, I feel like I'm back to being harassed by a sorority girl who's complaining to our e-board that she wants to do a beach-themed mixer with sand all over the house and backyard and not a more normal theme. 

Whenever I hear someone with this accent (gays included and some straight guys for some reason) I just automatically assume they're less competent at their job versus someone who talks in a more polished/normal voice.

Does anyone else thing it's crazy that junior bankers who are women/gay are still talking like a 19yo sorority girl from SoCal and still being taken semi-seriously by clients and the rest of the bullpen?