Comment by pcarroll
This works fine for your end. But the issue we are addressing is on the other end, when you don't control the network and need to reach devices. If all customer sites are running rfc-unroutable blocks, you eventually encounter conflicts. And the conflict will likely be with the 2nd one you try.
I mostly wireguard in from my work's guest wifi and people's homes. The first I don't have access to anything internal anyways and it doesn't conflict and the latter mostly use default 192.168.1.0/24 so there's no conflicts I've hit there so far.