and...I mean, there really isn't anything wrong with SNR.
Well, yes and no. SNR is deceptive in itself if people just look at the biggest number as being the best, like they do with SINAD.
More voltage/output swing and your S/N ratio goes up all other things being equal. You can have a noisier (residual) amplifier or preamp with a much higher output swing and it will achieve an SNR greater than an amplifier with little residual noise and a lower swing. Not really fair.
That's why the S/N (SNR) at a fixed low level with HPAs is so useful. S/N on power amplifiers is always referenced to full rated power, so a 500W@8R amp will get 10dB more S/N by default over a 50W@8R amplifier. There is a high possibility the 50W amplifier also has less residual noise, but the big amp wins the SNR numbers game. SNR must be referenced to an rated output value and often, manufacturers are not specific or deliberately play games to get a better number.
Referenced to 1W is a killer for big amps as they often have a decent amount of PSU ripple due to massive transformers close to the front ends etc, so A-WTD tends to get published or a 400Hz HPF to get rid of the mains harmonics.
There was a push to rate amplifiers in dBW at one point. It sort of fell by the wayside, even though it wasn't a bad idea, just that people didn't get it and wanted to see "raw power" numbers in spec sheets.