1. "Unpatched servers become botnet hosts" - true, but Tailscale does not prevent this. A compromised machine on your tailnet is still compromised. The botnet argument applies regardless of how you access your server.
2. Following this logic, you would need to license all internet-connected devices: phones, smart TVs, IoT. They get pwned and join botnets constantly. Are we licensing grandma's router?
3. The Cloudflare point undermines the argument: "botnets cause centralization (Cloudflare), which is harm", so the solution is... licensing, which would centralize infrastructure further? That is the same outcome being called harmful.
4. Corporate servers get compromised constantly. Should only "licensed" corporations run services? They already are, and they are not doing better.
Back to the topic: I have no clue what you think Tailscale is, but it does increase security, only convenience.
The comment I was replying to was claiming that using your computer 'poorly' does not harm others. I was simply refuting that. Having spent the last two decades null routing customer servers when they decide to join an attack, this isn't theoretical.
As an aside, I dislike tailscale, and use wireguard directly.
Back to the topic: Your connected device can harm others if used poorly. I am not proposing licensing requirements.
It’s why Cloudflare exists, which in itself is another form of harm, in centralising a decentralised network.