Some people feel that way, for sure. I'm cool with Who as a multitude of possible canons, and don't feel too tied to the reality of it. It was Who with a very mid-to-late-90s sensibility, they basically did that to kick up the gritty action!grrrl quota, which at the time was a bit more fashionable for its own sake. (I personally think it came off as trying a bit too hard, but I see why they were doing it.) And they don't quite break up; it's more sort of on-again-off-again (after a few good old-fashioned 7/Ace adventures). And then they try and end it with a nod towards the Masterplan, where Ace does kind of take up a little Doctorish apprenticeship thing.