I was still completely mystified until your last sentence. And now I'm just mostly mystified. I, too, keep hearing Tailscale Tailscale Tailscale from HN commenters but have no idea why I'd need it. For anything I need to access on (or from) my home network I just use a VPN I've hosted in my home for the last decade or so.
If you've already got a VPN solution your happy with, Tailscale probably adds very little value for you. It's just basically the easiest / most user friendly way to setup a VPN to your home network.
It can do way more than just being a VPN-to-home, but that's how most users use the free part.
It's still valuable. You can access your server with your own VPN set up, but what if you want to share a server to a friend or a family member (examples includes VaultWarden/Bitwarden, Plex, Jellyfin)?
If this is on Tailscale, you can just ask people to install tailscale client and login using one of the IdP, then ask them to accept the node you shared to them, and they can immediately access the server.
The alternative would be 1) sending VPN configs over and maybe also configure their VPN client for them, or 2) expose the service on the Internet protected by some OAuth proxy which really only works for web apps. Neither is easy/trivial.
I'd guess a plurality of people are only sharing Plex with family members, and nothing else. If you only care about sharing Plex, you don't need Tailscale to give a family member access, assuming you have Plex Pass, since Plex does a proxy as you describe.