Absolutely correct. And I will offer a better example shortly. Your argument above fails when one considers that each chess piece may have to be bought before the game can be played. Your pieces may be different than mine, but they are both chess sets. The money spent on the sets is moot. (Perhaps Civfantics should ban anyone's base game because they bought a cheap base version off eBay for $1.)
Now consider 2K Games coming out with their own Civilization V HoF. By right of ownership, Civfanatics' version is invalid. For Civfanatics to offer a Civilization V HoF is like removing Sid Meier's name from the box and replacing his name with Civfanatics' name. Thus Civfanatics offering an HoF needs to be clearly called what it is: something based on Civilization V. This is exactly what the current gauntlets are and what your example above is: merely moments in time where players agree to play under certain rules. The current HoF for Civ V is nothing more than a limited gauntlet.
Furthermore, consider the times in which we now play. Is it possible for 2K Games to make Civilization V HoF entry as simple as a 2-step process: buy Civ V, play Civ V? Steam does the rest. In fact, such a Civilization V HoF venture could be called "official" and sold as DLC. Also, Steam can handle any "merchandising" one may expect from an HoF in general.
No, the time has come for Civfanatics to deprecate it's HoF.