[300bps]

Sure. I work at an investment bank with hundreds of SQL Servers self-hosted myself. Your original comment I replied to said:

it looks like you want them to open their db up to the world?

What I was trying to say was that this is not the case. With Azure, it takes 10 seconds to open the firewall for a specific IP address. With a self-hosted firewall it probably takes longer but it's still not "opening their db to the world" as you stated. It's opening a hole in the firewall for a specific source IP address on a specific port with a specific destination IP address protected by a strong login and password. So, open for one person, closed to the rest of the world.

Your alternative is not to use the service.