I'm on Lemmy.world because it's the only instance I could make a account on the day Reddit shut down the API. All of the other popular instances had account creation stopped because of the flood of people.
I could probably make an account on another instance, but I'm pretty lazy. I honestly don't know what the benefit of using another instance would be.
The benefit is more so for other users on other instances. Lemmy.world in particular is causing a lot of trouble for small instances hosted outside Europe and North America. For example in aussie.zone local communities comments are taking 8 days to arrive from Lemmy.world because of the latency and how Lemmy processes federation serially. Hopefully in an upcoming release we'll get parallel processing of federated activities making this less of a problem