It would also result in a metric shit-ton of traffic and data storage.
Really depends how many instances they want to federate with. I run a single user instance for all of my personal Lemmy use. Looks like it is using 20Gb of bandwidth per week, and the VM it runs on only has 32Gb of storage (and it runs other services, too)
I used the Lemmy Ansible method to deploy. At the time that I first installed it, it was the recommended method vs a docker compose. It is a little bit of setup, but is pretty simple to get going. Just follow the instructions and it should just work.