Not that it matters, it's still an excellent example of stuff not working because links don't work as links anymore.
"just" is not an appropriate word here. There's a ton of functionality in the native UI and non-WebKit code.
I don’t know whether that’s right, but I read “We have a conditional access policy that requires a “compliant” device to succeed the SSO login. However, only the iOS Edge browser can prove compliance” as “our access policy does not allow logging in from Safari”. If that’s true, it’s not something Edge or Safari does or doesn’t do.
Being a "Managed App" through MDM/Intune. Typically it's used when installing corporate apps in a BYOD scenario. The managed apps are isolated from information sharing with unmanaged apps, e.g. policies can be applied preventing copy/paste, access to Files.app, etc. It (and it's isolated storage) can also be remote wiped without nuking the whole device. Edge.app still uses the Safari rendering engine, etc. like is generally the case with 3rd party browsers on iOS.
You can't do this with Safari.app unless the whole device is managed, which doesn't work well for BYOD.