I personally haven't deployed it though I've toyed with it, but I think as well as UI and integrations a core topology differentiator is that, like Nebula, Tailscale does/can do meshing. Plain vanilla Wireguard is pure classic hub-and-spoke, which is 100% fine for a basic VPN use case like "I'm out somewhere on the WAN and want to talk to this LAN stuff" or "I want to tunnel some/all my traffic through some specific alternate exit".

But say you've got main site A which has a public static IP and is where support is for administrating others, site B which has a full backup server but no public IP, and then sites C/D/E/etc where people are doing work and having significant on-site storage and comms needs, all of which are behind typical ISP NAT from multiple different ISPs with no static IPs. Everyone wants to be able to do high bandwidth things like video chat directly together, or back up/restore to site B. Plain WG could do that, but would funnel it all through site A's link which isn't very scalable and likely to become a choke point in a hurry. A meshing VPN can let two private sites talk directly with a public address only serving to facilitate hole punching and setting up the connection each time. It's definitely of real value. Another thing would be not bandwidth but latency. If you're within a few hundred miles on land that probably is irrelevant. But if different sites/people are across continents adding an unnecessary extra hop may become a very big deal even for simple web apps. Resiliency also enters the equation, what if site A goes down? A mesh can help with those too.

Then Tailscale adds a lot of cool QoL on top. Meshing does raise new challenges in terms of access control vs when everything is funneled through a single convenient point. But regardless, other topologies can be of basic interest too even without extra sugar.