For the same reason why I don’t use Qubes-Whonix for everything.
Downloading, uploading, gaming, streaming, video calling, banking, etc. all suck when using Tor.
No proper stream isolation, unstable, only works with TCP, high latency, slow, blocked by a lot of sites and services. That’s why I stopped using it system-wide.
The alternative solution is using Orbot system-wide and a VPN in a work profile.