I've Sometimes Wondered - Why Such Reactions??

Mozart called Clementi a "mechanic" (even though more of Clementi's piano music than Mozart's was found in Beethoven's personal library).
Chopin called Beethoven a "thumperer"; also, a "noise-maker."
One of the composers in the group that included Moussorgsky once stated that "Moussorgsky's music should be placed at the bottom of every ash-can in Moscow."
Tchaikowsky called Brahms "that artless bastard."
And there are more of these kinds of statements made by great composers about other great composers - what about Wagner calling Brahms a "prophylactic composer?"
I've sometimes wondered if there is an indefinable, actually physical (chemical??) component that innately protects some of the great composers (certainly not all) from any palpable influence - could that be a reason for such reactions?
No need to take me seriously - only a whimsical form of theorizing on my part.