But most of that is nothing to do with compute. A rack of servers is all compute. Starlink sats are antennas, RF amplifiers, solar panels, laser links, shielding, even maneuvering thrusters and fuel for those (they could be electrical ion thrusters but they'll still need reaction mass, not sure what type they use). Probably some inertial reaction wheels too, they are used for spacecraft orientation, not positioning.

They are sending a few racks of stuff up every launch but the problem is not that it's underspecced. It's that most of it is just needed for equipment survival and communication in space.

You're talking about an environment that's full of radiation and goes from -200C to +200C every 90 minutes. That needs to be orbit managed and cooled (and sometimes also heated) without any airflow. Just sticking a few servers in a barrel isn't going to do the job.