I don't know if compute shaders were the reason for the GL 4.3 requirement, but from own experience, having to support different GL versions in the same code base isn't exactly trivial without resulting in a granular #ifdef-mess.

The cleanest solution is to have different backends for different GL versions, but that means a lot of duplicate maintenance effort and code.

But tbh, any cheap laptop made in the last decade should be able to run GL 4.3.

The only exceptions I've seen so far are VMs and the Raspberry Pi.