I think OP has a similar problem to me, which is that for a lot of search queries you end up on shitty content farm websites that don't have anything of value on them. Reddit, Quora, etc will generally give you an amateur's perspective on topics, but at least it is a perspective that was written by a person who gave a shit.
For example, if I look up a given book. The first results will be amazon and good reads, fair enough, but the reviews have been gamed so I'm not going to bother with them. Then it's the blogs that have managed to figure out SEO. They read in a similar style to recipe websites, and I haven't seen any good ones in that category. Then I will find a reddit thread about the book, hopefully on a subgenre subreddit and not just r/books, that convinces me to get it or not and has recommendations for books similar to it.
If you get far enough you will find some personal blog that doesn't care about SEO. HN has link farm threads every now and then where people post theirs, and I have seen some individuals who post insightful book reviews, but you will not come across those in a search engine.
I think they mean that they add "reddit" to the end of the search strings they submit to Google.
Often if you're looking for discussion on a certain topic it's a reasonable starting point for a lot of things.
