I would not even expect any airline to keep track of actually flight history beyond 2 years. What value does it have for them to keep that information. Sure, they may want track revenue in summary but really don't care where you went.

I have boxes of receipts in a closet from submitting expenses to clients that every year I say I am going to toss them out then I go through them and get nostalgic about where I have been and put them back