I think it's more than nothing, though app monetisation may still be enough to justify the loss. The vast majority of users do not contribute content and they certainly don't help moderate communities - a lot of the content that is good on reddit either comes directly from or is facilitated by the people who care a lot, and those people are the most impacted by third party apps going away, old reddit being abandoned, moderation tools being weakened, new reddit obsoleting per-subreddit CSS, etc.

reddit was the place for a lot of communities (and for the most part still is) but there's a lot of places on the internet you can get generic mass-market content, that might be what drives reddit's bottom line but it's not what makes it special. The masses will go to the next popular platform, people interested in specific communities will stay as long as reddit doesn't piss them off. The beauty of reddit is that you can be interested in one or two niche communities, but you soak up the rest of the ecosystem along the way. If the masses go somewhere else and the niche communities are pushed away, there's not much left.

Also to clarify, I don't mean niche as in small, I just mean specific hobbies or interests etc, that's what reddit was good at - not needing to go to some forum to be able to talk about your thing. And by masses I mean whoever is participating in r/pics or r/funny or r/tifu or whatever else.