CMD.exe is either a program accepts either a filename or URL in the same context (VLC does this), or the user is confused about the URL/file distinction. The .ZIP TLD was concerning for this reason.
I was looking more for specific dangerous use cases; for example, "The user types such-and-such in the address bar, and instead of getting this he gets that." In other words, how is this a problem in actual practice.
An example:
The attacker posts a message to a forum, chatroom, etc. like:
Download: 2024YourCompanySalaryData.zip
When the user clicks "2024YourCompanySalaryData.zip", it is actually a domain name, and loads that website. This website then asks you to enter your corp credentials, or executes a 0-day on the victim's browser, etc.
The forum doesn't need to allow file downloads (i.e. a real .zip might not even work), and even if it does, client or server side virus scanning doesn't have a .zip to inspect.
The user is less wary of phishing, having never seen the .zip TLD. They assume they are downloading a file.
https://blog.talosintelligence.com/zip-tld-information-leak/
In terms of the user going to a site instead of a zip file: If a user is willing to unpack and run a random file he downloaded and give it credentials to something... what's the difference? Not being argumentative, but this seems like a stretch.
Now "foo.zip" is a valid URL.
You could have a forum or chat program that you think is quite safe, since it doesn't allow file uploads, and doesn't allow arbitrary link text, and this would upend that.
Interesting idea. Can you give an example of how that would actually happen? Also the cmd.exe one. So what if it's a valid hostname?