I fail to see how, even if The Dalek Invasion was erased, or changed so they would win, it would in anyway erase Susan from time?
As I've already explained to you, that is not what I meant in the first place. That's just your misunderstanding of what I meant. I'm not going to defend a position I never actually took.
Anything not directly aimed at Susan that erased her because of a change to the way the Invasion played out, would've erased the Doctor also, since they traveled there together, not beause of the Invasion, but, simply by chance
You're overthinking it. As I already said, Doctor Who
is a tall tale written to appeal to the imagination of a child. It's not supposed to hold up to detailed logical analysis. Of course
it doesn't make sense. Doctor Who
has never really made sense, especially not where temporal physics or causality came into play. Things happen however the story needs them to happen. Russell T. Davies needed the Doctor to be the last Time Lord, and that's the entire explanation for why he's the last Time Lord.