Most free web sites pay for their upkeep with ads. It has been an unwritten agreement since forever (or at least as long as there have been ads on the web) that if you consume the content, you pay the creator by looking at the ads on their site.
Consuming the content without looking at the ads is like shoplifting because you don’t like the way a store’s checkout counter works and/or the fact that they want money from you at all.
That’s certainly a good explanation, but it really calls into question the viability of a sub like this. On reddit, the engaged folks drown it out and mostly keep the unpopular opinions intact. This and the super highly-upvoted political stuff just makes it look like this sub has no purpose at all.