Agreed, mostly. The two "Tyranny of Dragons" adventures together are probably roughly equivalent to six volumes of the Pathfinder AP, minus the non-adventure 'support' material. That, in turn, seems to be roughly equivalent to the 12-part adventure paths that used to appear in Dungeon.
But, at a guess, that's probably closer to the 8 adventures in the original 3e Adventure Path ("Sunless Citadel" through "Bastion of Broken Souls"). I would be surprised if it was equivalent to 12 such adventures, though I might be wrong.
This is true, on both counts - it's less expensive to do one supermodule than six standalones, and the return is better.
However, from the fan's perspective it's easier to budget for six monthly payments of $20 than to budget for two $40 purchases. Especially if that $20 is a consistent monthly expense, and double-especially if I can just set up an automatic payment and forget about it (as with the Pathfinder volumes). That's one of the definite advantages of a subscription-based approach.
That's not to say any of these is "the right" approach, or even that any of them is better than any other. Different weightings of the priorities will give a different result, is all.