Some people might find the answer to be obvious (yes) but I've rarely found it so. In fact, this is a question I often find in the linux community (regarding linux going mainstream, not lemmy) and people are pretty split upon it.
On one hand, you may get benefits like more activity, more content, more people to interact with, a greater chance you'll find someone to talk to on some specific subject.
On the other, you could run into an eternal September like reddit, where Lemmy would lose its culture, and have far more spam and moderation issues.
I think in the future people will care much more about free software and privacy, so it's inevitabile that federated platforms like Lemmy will be mainstream.
Reply: I would like enought people to have more quality contents so that I can drop Reddit.
Also more people means more interest and at the end a better software.
Yeah, this is what I'm waiting for on Lemmy and Aether. Just enough activity across just enough topics that I can finally drop Reddit.
Only problem, with some of these federated and P2P protocols, is that, for the time being, the kinds of people who leave mainstream social media tend to be fascists, qanon nuts, or straight up delusional to the point of likely needing medical intervention.
Pretty glad I discovered Lemmy though. Everyone here seems fairly sane.