Not really. It's a bad idea to bury past decisions that deserve some sort of "no trespassing," "thar be dragons," or "do not feed after midnight" monument off in some historic commit in version control. The problem is that VCSs are completely undiscoverable inside the flow of walking through code to see "where's the right place to implement this awesome feature idea I had." What you might not realize as you start implementing that feature is that it's already been implemented 5 times and removed.

A comment at the end of a "go to definition" chain serves as a good dead-end indicator that can save lots of overhead and wasted effort.

Yes, in theory. In practice, you'd not only remove this function but all of its calls. When somebody down the road realizes that they want this function back, they have to (A) realize it's in the VC history and (B) not only get back the function but all the calling points. That is so much of a pain and potentially error-prone that leaving this function in for a while with a comment might be the more practical approach.

No. Replacing that with a magic number wouldn't be good. Maybe it could be a constant instead, but this is most likely good practice.