Compare the hardware specs of the PS3 with the PS4's and the general(ly available) specs of today's PCs and you will get your answer (hint: yes, it is holding back development). Nobody's gonna be able to give you a specific list of content/features that had to be curbed or held back just because of the PS3, since only the dev team has that knowledge, but many have pointed in the right direction in their answers already.

As for what Yoshi himself says... I do think we should've learnt by now to take it with a pinch of salt (COUGHpersonalhousingCOUGHcashshopCOUGH). Yes, he is "The God" of all things FFXIV, but as such and as a public figure who's at the center of most (if not all) public events, he's just as much a PR person as well. He does have a product to sell - to potential new customers too, and not only inform the regular playerbase about changes and new things. Anything that could cast a shade on that is apparently not said until the last minute.