I would suspect it's because everyone has their own, individual tastes, and even for the people who prefer PRO, most of them don't feel the childish need to disparage another show they like less or dislike.
I suspect many of us also take exception to the intransigent insistence on using the perjorative ‘STD’ when that is not and never has been the short form for Discovery. (We haven’t see ST:TOS and ST:TNG in use in decades.)
I love Prodigy and am advocating strongly for its return. What I have no tolerance for is denigrating another show in the franchise, that has been successful in its own audience niche, to promote the ones I most wish to see.