Unlike all the other adapters?
Yeah, but it's one thing to make an adapter to play games for an 'inferior' system like the 2600 (so new owners of a 5200 or CV could keep their VCS games but sell the console upon upgrading). It's quite another matter to make an 'adapter' for the 5200 to play CV games (a console which it's not only on equal footing with, but which it does not share a similar CPU with).
You are somewhat correct though that all of these adapters sold back then basically replicated the original system, and were essentially pointless gimmicks.
Well, to be fair they did minimize the number of power cords & TV hookups, and the amount of console storage space you needed. Plus it was a great thing to be able to tell your parents, "If you buy $New_Awesome_System and the $Old_System Adapter for me, I'll still be able to play the hundreds of dollars of games I own, plus all the new games for the new system!" That was especially important if your family only had one TV, and the system had to be hooked up to it. It was unlikely you'd be allowed to have more than one system hooked up to it.
At least, that was my experience. What was yours?
Hey does anybody know what was up with those COleco game that looked like Atari games?? I would often get mixed up at the identical titles and similar catridge bases.