Mainly because Tailscale is popular with the HN crowd. Many people use it for their personal home networks, and some companies do to (we do at Instacart).
The nice thing about this is it means you can invite anyone into your network without requiring them to have a Google/Apple/Github account. They just need a phone. It also means you can be much more confident inviting these people because they are unlikely to get phished due to a crappy password.
One of the common complaints in HN comments about Tailscale is they don't want to trust Google/Apple/Github/etc for various reasons. This removes that need.