A mesh-type wireguard network is rather annoying to set up if you have more than a few devices, and a hub-type network (on a low powered router) tends to be so slow that it necessitates falling back to alternate interfaces when you're at home. Tailscale does away with all this and always uses direct connections. In principle it is more secure than hosting it on some router without disk encryption (as the keys can be extracted via a physical attack, and a pwned router can also eavesdrop on traffic).