See, all explainable.
I don't think you explained anything. Tube always has inferior freq. response to SS amp and higher distortion but most people will favor tubes due to its more musical nature. Of course if a bad tube amp very high distortion you can tell, but most tube amps nowaday are pretty good.
FET amp with its being a square I vs. V curve sounds more tube like but its weakness is that it is less transparent vs. Bipolar and not as dynamic.
Here is the thing. The freq. response curve and distortion will only tell you so much. How can measurement tell you if it is a FET amp or Bipolar amp? But a quick listening will tell you the difference between a FET vs. Bipolar. FET amp has gotten much better now, but in the old day it was very "hazy" vs. Bipolar. A lot of amp now uses FET as an input stage and Bipolar at the output stage. Just like using tube as input stage then SS as the output.
Also if you look at a speaker freq. response and distortion, it is an order of magnitude (or even higher) higher than anything audio chain (amp, preamp), so measurement would tell you that it will dominate anything in the upstream components, it is not. You can hear the difference with different amp or preamp.