We don't have a good sense of which instances are going to be durable long-term yet.

Additionally, If you only have one instamce, you're signing up for that server's bespoke curation of the Lemmyverse.

I currently have (I think) 5 accounts spread across Lemmy and Kbin for these reasons.

I remember when I first heard about it around 2000/2001. Interesting idea of distributed hosting of all material, but at the same time seemed like something you really needed to go all-in on to get any benefit from it.

Coverage at the time was mostly "you'll never know what horrible things you're hosting on your own machine."