I used to have Reddit whitelisted until they started showing subreddit-targeted ads in other subs. I follow a bunch of cryptocurrency subs and the ads there are… well… as you expect.
Why is this bad? You follow cryptocurrency subreddit, they show you relevant ad. You follow "warm mittens" subreddit, they show you relevant ad, etc. So why is it a bad thing?
I can't speak for the GP, but in this case of the cryptocurrency sites/fora I frequent (including topical subreddits), the ads are for idiotic scams. This indicates that whatever vetting they're doing is insufficient, and so they can be safely blocked (specifically -- if they can't be trusted to not display ads for obvious fraud, they can't be trusted to vet ads for other malicious attributes).
