I mean there are probably a few super edge cases for something like this. A digital art display, or theater production for instance. Something you can custom 3d print yourself is just about perfect for that.

lol brrrrt. Actually there's heaps of cases. Traditional servers are large, power hungry and generally 10-100x the compute power most jobs need if you buy a piece of hardware for a site. Traditional server also requires expensive monkey like me to service.

RPI rack on other hand. plug and play. Cheap as chips to keep failover as you can keep backup rigs in a cupboard. It doesnt require expensive monkey to unplug bits. Most sites I serve have minimal if any internet at all. So cloud compute not an option everything has to be done on-site. RPI is perfect. It has more than enough grunt, costs bugger all, performance is rock solid.