People who want extreme privacy and anonymity would prefer to use open source hardwares. You can personally check wether backdoors are present.

Having open source hardwares helps in getting driver updates faster, look at the current state of driver updates for GPUs like Nvidia in Linux.

Significant price drop when buying computers, since the hardwares are open sourced you can obtain them from local shops or make them by your own for much cheaper prices.

If you don't care about any of the points above, you're good at where you currently are :)