The best way to improve image quality?
Become a better photographer!
The best way to improve image quality is, in fact, to improve one's skill as a photographer. Even when quality of gear becomes an issue, the ability of the photographer to diagnose the issue and know what is needed to correct it is still the paramount consideration.
Apart from the fact that it is a basic truth, I see no rude or abusive language in the answer.
How is encouraging someone to improve their skill as a photographer rude or abusive?
There is no abusive language in the four original words of the answer. There is nothing "calling out" or identifying any particular individual.
I must admit that at times I just want to reply to a user who asks, "What gear can I spend money on to make my pictures better?" with the following, but this wasn't one of those times:
Someone please enlighten me.