At least scifi-plotwise, the problem with this model of time travel is that it assumes arbitrary events are marked as "important", but from the perspective of the timeline, all events should be equally important -- or rather, none of them are.
And if every event is important, and must happen (in some fashion, even if you somehow stop it) and must be maintained... then you can travel to the past, and do nothing at all. Because everything must stay the same.
If you imagine that some key events are so special as to deserve recognition for maintenance, then there must be some author to this grand narrative
IMO the only time structure that has a chance of a plothole-free narrative is multi-universe (time travel = pick a universe thats exactly the same but delayed to point of interest, out of infinite selection). If you want to get real fancy, homestuck-style multitimelines hopping back and forth between each other