What keeps you from accepting other peoples gear choice?

Based on one hand on a recent spate of threads and on the other hand on something which seems to be a tradition around here, I got to thinking a bit (yes, I know, novel approach, but it does happen even to the worst of us): what is it that keeps some people from accepting other peoples gear choice?

We repeatedly have threads and posts which can, one way or the other, be condensed down to my gear choice is the best, and yours is wrong. You can substitute any gear here, be it mirrorless, DSLR, smartphone, Sony, Canikon,whatever. The central behaviour is always the same.

So what causes it, what causes you to not accept other peoples choice? What is your reason?

Oh, and need I say it? Try and keep it civil

Regards, Mike