People often compare Oyster to Sia, storj and BAT ... here is an interesting review to read:

https://www.reddit.com/r/Oyster/comments/7x6804/info_why_oyster_is_better_than_bat_sia_storj_why/

My point to the comment that says that people won't want to give their CPU power to "mining". Rendering ads also consumes power but what is worse, it slows down the website loading and when on mobile, it consumes mobile data... Personally, I would love to give anything but mobile data to website owners to generate revenue.