Three of the top 20 list on distrowatch are Arch or Arch derivatives, including the number 2 spot. Its wiki is widely recommended as well for users of any distro.
"Niche" is a bad way to describe Arch.
It's probably more likely that a person interested in setting up WireGuard and their own VPN are running Arch or a derivative than any other distro.
I love Arch's wiki and the userbase's enthusiasm. But how in the world do you think Arch is the most probable distro base for a wg user? Using your distrowatch reference, 4 of the top 5 are Debian based.
I was looking at it from a perspective of who would be likely to install WG and set up their own VPN. This is me guessing (that's why I hedged and said probably), but I suspect there is great overlap in the tinkering and DIY attitude of Arch users and WG users.
Mostly I was responding to the statement that Arch was a niche distro.