Not necessarily, I think people are oversymplifying this thing...
If game X runs at a very solid 30fps on both machines, all the effects, textures, etc. look the same, well then there is something fishy.
However a team may have decided that they prefer to raise the shadow quality use a better AA solution, etc. on the PS4 version (I think these are bad choices, I.E resolution is more important in most cases) so the rendering resolution would still be the same, but the PS4 version would still have some benefits.
Grayer areas are situations like Destiny, it's 1080p30fps, was developped around that resolution and frame rate in the first and the XB1 was probably very close when MS updated their SDK... Now should the PS4 have an unlocked FPS option, certainly, it's almost sure it runs at 60 most of the time or close enough to it that is would be a net benefit :-/ at the very least it's a situation like Tomb Raider:DE (I.E. much better than locked 30).
Now about MS enforcing this, the only parity closes we had confirmation of are the content/release date closes, but MS has been known to sabotage other companie's products actively (Netscape, Oracle, Wordperfect with undocumented windows updates) ... so why not? they're not the kind to try to just create a good product and hope it will work, they will put as much efforts in causing arms to their competition as they put into creating whatever they are set out to do, they ended in court many times for this kind of behaviour.