I encounter this too. Safari’s new features interfere with WordPress editing so I now do that in Edge. I do all my forum work in Brave. I have a bunch of specific Firefox profiles for a bunch of different purposes.
The difficulty we face is having many feature requests, so every feature has an opportunity cost and we always proceed carefully to avoid introducing bugs. So it’s always a delicate balancing act. And there’s the complexity of the UI to minimize. This one in particular has implications: it would need a UI to change the default web browser used for the specific URL.
Internally, we have often discussed this more generally with respect to files. Hook takes the simple approach that is easy to explain: Hook delegates the opening of files to macOS; when you open a hook://file/ URL, the same app is used that would be used if you were to double-click on the file in Finder. Sometimes it would be useful to open the hooked file with a specific app. But that too adds to complexity and also the complexity of undoing configurations. What if later you want to change the mapping when you have many hooks pointing to the same thing, and many hooks in the system? We would need to add a lot of logic to enable users to do that right. So it’s tricky.
The browser-URL mapping subject is also discussed here: Open Hook Links in Different Browsers - #3 by stevelw