I didn’t think that Matrix was considered part of the fediverse? Lemmy and Piefed are redundant since their core functionality is very similar, unless the two accounts are to segment your online personas, like politics, NSFW, and everything else. I had never heard of vutuv until now.

Many fediverse platforms do have specialized functionality so it’s beneficial to open an account for them specifically. Here’s a good reference article with guidelines: https://fedi.tips/using-multiple-accounts-on-mastodon-and-the-fediverse/