No argument there, but messaging is important to be effective. Most US voters are going to reflexively balk at the word "socialist" and will stop listening to anything else being said. It's unfortunate, but it's reality.
I think they'd actually agree with the tenets of socialism if they could get past the reflex though. For example, if "owning the means of production" were packaged as, "a fair share" they'd be more likely to listen. Silly, but you have to meet people where they are to be effective.
Mamdani talking about issues everyone but the rich would agree with is great, and I'm happy to see the upswell of support for it. I still think he'd lose in most other places in the US though, the word "socialist" just carries too much of a stigma outside the major metro areas.