I have it on good authority that this is something new they're doing. And it's intentional.
Here's the scoop. Colt recently hired a new engineer, and part of the onboarding included review of the TDP. Well, this new guy stumbled across a footnote that had been overlooked for decades; that a properly spec'd rifle must have a FSP with a very slight "T" profile. It's far too technical to go through why this matters. Just trust me; it does. Simply put, without a proper "T" profile FSP, a rifle cannot be considered mil-spec.
In case anyone didn't pick up on it, I'm being incredibly facetious. The sad thing is, if the above were true, there'd be legitimately serious comments asserting whatever brand rifle isn't any good because it doesn't come with a "T" profile FSP. I'm actually not kidding on this point. We already see this with the F-Marked arguments.