Re: How exactly?
By prefixing all their webpages with the Edge prefix.
When such a page gets referenced, it will be opened, not by the browser the user is using, but by Edge. It will not be visible to Firefox or Chrome.
Any plug-ins, such as NoScript will not have chance to scan the page and apply its rules to it, so anyone using Firefox will be vulnerable to such links.
Anti-malware providers will not be able to put workarounds into their products because MS will say they have reverse-engineered their code.
Ok, anti-malware utilities and browser plugins could be tasked with scanning every webpage for edge links, but it is easy to obfuscate such links: this would apply to browsers as well as email programs such as Outlook and Thunderbird.
If this is still not clear: please respond. I think this is important to understand. I may, of course, be wrong.