It can be, depending on the nature of the software. However, for a heaping ton of software (such as libraries or software that is meant to be used without internet access) it can be the worst option.
The real answer, as always, is that there is no universal one-size-fits-all solution to this.
For the majority of things I do I just want to shove data in one end and get data out of the other end without ever having to build a UI or wondering if it's "up" or "down".
That is not appropriate for all sorts of software. For a lot, though, sure, that can work. It's just not a universal solution.
A web browser?
And somehow they were linked. Deleting one deleted the other.
You could open the HTML page from your disk, in Internet Explorer. No internet required.
Update: they weren't linked at the filesystem level. Explorer.exe tracks .htm/.html and a folder_<something> together: https://learn.microsoft.com/en-us/windows/win32/shell/manage...