Because AMD GPUs don't have proper ray tracing support. Hell, they can't even do frame generation.
Believe me, I'd love nothing more than to own an all-AMD PC, but until their GPUs are as good as their CPUs, I'm stuck with a hybrid machine.
For it to be very hard if not impossible to swap in Laptops I agree, that's true. For desktops it should be a drop-in replacement tho, considering the equivalents of AMD to Nvidia all need the same, if not less, requirements (Power, Other components, Plugs). Selling my 1070 I would get ~100€, which is the price of a used RX Vega 56, the AMD equivalent of my card. Considering I want to upgrade in the near future that would be pretty pointless however.
Because AMD GPUs don't have proper ray tracing support. Hell, they can't even do frame generation.
Believe me, I'd love nothing more than to own an all-AMD PC, but until their GPUs are as good as their CPUs, I'm stuck with a hybrid machine.
That's also the situation I'm in, I was also 12 when I got my PC XD
But now that I got my RTX 3080 working with NixOS, I don't think I'll swap it.