Wireguard is not an alternative to Tailscale, any more than FTP is an alternative to Dropbox. And not just because Tailscale actually uses Wireguard under the hood. Also if your comment is a sarcastic callback to the "why don't you just use FTP" comments when Dropbox came out, well done.
Wireguard is a great VPN protocol, but what the basic protocol doesn't do is make it transparently easy to use in a wide variety of edge cases without having to reconfigure anything. If all I want is two devices to be able to talk to each other, at least one of which is in a fixed location where I have total control over the network, then yeah, raw Wireguard is probably a decent solution. If I want to do anything else, I need a management layer on top of Wireguard, and Tailscale is by far the best solution for that out there.
As a thought exercise, consider a home network where a laptop connects to a NAS to store media files. I take the laptop to some random destination and connect it to hotel WiFi, while someone else takes the NAS to a totally different hotel and connects it to the WiFi. With Tailscale, the laptop can immediately directly access the NAS without even having to change the mount point. Think about what it would take to set up similar functionality with raw Wireguard. I'm not saying this is a common scenario, or that you can't do the same thing manually. But the fact that such a setup would just work is pretty impressive.