To be sure, is it possible that, on each subsequent iPhone release, the hardware got better at handling weak signals, and thus a mediocre signal for iPhone N was decent for iPhone N+2 and would give great throughput on iPhone N+4?
Possible sure, but wouldn't it be better marketing for the iphone to have better performance on lower bars? Phones are judged for their performance, but network providers for the number of bars they show on the screen.
Bars are supposed to be an indicator of actually achievable quality of service, in my view. I don't care why I can use my network where I am, I just want to know whether I can.
The comment you’re replying to is incredibly concerning. Is he saying people at Google are purposefully misrepresenting signal strength so they can “compete” with Apple?
Except you have no idea why Apple is changing the signal display. They could be lying, or they could have a standardised test in which newer hardware performs better. This guy, on the other hand, is clearly saying that Google has no such thing and they're blindly copying Apple regardless of the performance of their hardware.