I don't think picking an arbitrary time of, like, 9 years ago is accurate for when the western left's "idpol turn" started. Labour rights and anti racism have always been closely intertwined causes and the trade unions have been closely aligned with queer groups since the 80's at least.

But whatever.

What has that accomplished?

Created a more organised front against the current reactionary pushes and helped getting marginalised people politically active despite the neoliberal attempt to crush grassroots political activism.

Who has it helped?

Plenty of people, myself for example: leftist agitation caused both a reform within the Welsh NHS' gender service to move away from antiquated gatekeeping and towards self-id and informed consent, while at the same time these same groups successfully pushed the Senedd to bring out free prescriptions. My poor, post-grad self wouldn't have had the time to fight to get a gender identity certificate nor the money to afford HRT treatment if it wasn't for the intersectional tactics of the "western left".