I don't exactly view professional sports in the same category as pornography, but almost.
I think they are pointless and a huge waste of time and money. I think they have a largely negative societal impact. Pornography at least has a point.
There is no good reason to waste my child's time or my time on junk like that. I have better things to do than cheer on overpaid, steroid enhanced football players pounding the bejeezus out of each other. If it floats your boat, that's fine, and I don't care whether or not somebody else wants to get involved. That is also kind of how I feel about porn, come to think of it.
There are lots of things my kids are going to remain culturally ignorant about for as long as is reasonably possible. We don't immerse ourselves in gang culture, listen to rap music or watch reality shows or cable TV. So far, the kids are doing pretty well, despite the deprivation of not owning football jerseys.
Our elementary school also had days when kids were supposed to wear jerseys supporting their favorite teams, but it was much lower key than the OP. We ignored it, and as far as I can tell, the kids don't need therapy.