Oh my, welp, I guess that showed me! How dare I not take into account a deleted scene from a serial made years and years before other serials added to the background of the Doctor?An episode during the Troughton era was originally going to make it explicit that Hartnell wasn't the very first Doctor but the line was cut, so objecting to a Showrunner doing exactly that makes very little sense to me.
While not a fan, I find it on the whole to be way, WAY better an alternative than this Timeless Children dreck. On the other hand, Cartmel was sensible enough to recognize that that storyline presented more problems than it solved, ultimately diluting the very mystery it seeked to deepen as a result of the stangant Davison/Baker years, thus why he is not resentful of the fact they never got to produce that storyline.Very well, demonstrate.
In the meantime, what do you think of the hints we got of the Cartmel Masterplan back around season 26? Chibnall’s not the first to suggest the Doctor’s past goes a lot farther back than we thought.
RTD even jokingly suggested it as per The Writer's Tale, for the Tenth Doctor's regeneration story, that as a result of his sacrifice he'd basically create the Time Lords and Gallifrey. But he also argued that no one would care and it'd be boring. Wise man.