I think it could be harm to components when you are writing in their non-volatile memory. Namely at least motherboard and GPU. Both often have flashable memory

I think it could be harm to components when you are writing in their non-volatile memory. Namely at least motherboard and GPU. Both often have flashable memory for BIOS/UEFI and VBIOS(for GPU). Interrupting power at wrong time when these are being written could result in non-functional components. Some models do offer dual-bios which lowers the risk.