I feel like most Javascript demanding websites already mine cryptocurrencies with their crowd's computers.
If one tried to find a comfort in it, it could be argued that at least now they will partially pay for it.
Then I think again and I think that it might increase this stealth mining even more.
Whatever viewers will gain, they will pay for it in their electricity bills, increased hardware wear and wasted time.
I am all for porn, but I prefer overt popups over covert mining.