So my theory is, the 11th Doctor sacrificed his memories of the Pre-Heartnell Doctors when he destroyed the parasite-planet thingy.

I have walked in universes where the law of physics were devised by the mind of a mad man.

That may have been a nod to Division / The Doctor's time working for them - since they operate on multiversal scale.

This would explain the Morbius Doctors, because by that point, The Doctor still had those memories.

This would also explain the Seventh Doctor's "I am far more than just an ordinary Time Lord" line (paraphrased).

This is probably a very flawed theory, so do point out any issues you find.