Quote Originally Posted by Clover_Blake View Post
[...]If it didn't exist, then the items wouldn't either.
That is a statement you can only know if you could observe two realities: One in which the shop exists and one without.

But let's go with this way too: If the shop didn't exist, more of exclusive shop-items would be available in the game. (via gil, mgp, achievement/effort etc.)
Also not something one can definitely be sure about... well, unless the one whoever decides to withhold something from the game to make it shop-exclusive ofc.