I run a Mastodon server. In one of the giant floods of new users, I installed Docker on an RPi that I already had laying around and used it to increase my asynchronous worker capacity. I doubt I would have gone out and bought an RPi for that, but I had one up and running anyway, and it turned out to be perfect for the job.

Note that I could solder my own boards together from bare PCBs and components. I just don't want to have to when someone else has already done the hardware work for me.