Don't know about the ISP throttling wifi speeds. That story seems full of misinformation. I have XFinity with the gig plan and I have a script running that checks my speed randomly on a raspberry pi. It consistantly gets 1200-1400Mbps. That is hard lined to the router (Nighthawk). Yet my wifi is different dependent upon the device. My Z Fold 4 gets 800-900 near the router, but go downstairs into the living room and its around 500-600. There are to many environmental aspects that come into play that will impact speeds.
And we do quite a bit of streaming in my household.