Why do niche subreddits often feel more authentic than massive communities?

Yeah, size changes the vibe a lot. Smaller subs usually have people who actually care about the topic, so replies feel less like farming karma and more like real discussion.

large subs, believe it or not tend to be filled with bots, spammers, mostly propaganda, and its mostly fake engagement. niche subs are more curated to a smaller group and its also easier to sus out potential botting and spammers. small subs have next to no spamming/bots, because they have a much stricter filter, must be discussing content of that site, and not babbling like you can in a larger sub like politics or news. example. is askdocs, they used to be more blase about who gets to give advice. now its restricted to verified medical professionals. and another example my work sub, if you talk about other than the work, like injecting politics its automatic ban.

Once a community gets too big, it can start feeling like a content feed instead of an actual community.