I think you can buy up-votes. Ton of ads on those front page posts.
Some hide that promotion side better than others.
I remember seeing this pic on the front page once. The top comments were calling it out as an ad.
The main Reddit page is just a commercial platform now. Politics, Celebrity PR, New Products, Software. The technical subreddits are still good though.
Oh yea, Quick google search. There are too many place to buy up-votes and down-vote the competition. I have never used one of these services, but here is an example.
https://upvotes.club/