Cant MS just provide a button somewhere that downloads and installs the browser? A computer doesn't need a browser to download something from the internet (such as a browser).
Being able to show a webpage is an essential function of all modern operating systems. the included browser is a part of windows, much like notepad and vi, or a package manager (programs control panel in windows), or regedit. You are free to add a browser of your choice. The one that's part of the base os image is not your choice, and is supported by the os vendor, as part of the os. You want an os interface to let you frankenstein your os with custom parts and make it unsupported? You have one. You, as an advanced user, can remove edge with powershell very easily.
re: corporate account - The WebBrowser component (MSTML/Trident) will never be removed because it would require replacing a huge part of the OS that handles this, in too many places, and it won't be replaced with WebView based on CrEdge because that has no support for proprietary Microsoft controls.
They will remove IE, but not Trident.
As far as routers, captive portal launches a browser on my pc, not a modal dialog. And none of the routers I have do what you say. I have to plug in a cable and go to the gateway ip. In a browser.
I'm not convinced there is much to gain from letting Edge be uninstalled through normal means as long as it's not consuming resources other than some disk space when you're not using it.
https://blog.jourdant.me/post/3-ways-to-download-files-with-...
There's also always the option MS could have done, disable uninstall of the last browser on the os, whichever that may be. So if you have chrome, edge and firefox and you remove 2 of them, trying to uninstall the third one would give a warning or stop you or something.
Happened with me once.