As a principle it's a bad idea (tm), exactly as putting addons in the 'official' ofp folders. But, it's also 'accepted practice' when the dll concerned is not part of a specific application. Eg, there isn't a mywhatsit.exe in a mywhatsit\ folder for the dll to be placed in. with a path=mywhatsit statement to go find it.
Don't know if you've delved into visual basic, but for vb to find a dll anywhere else than the listed default folders it searches is an excercise in futility.
all of which to say, you are right, but this was and is too convenient.