Peter B I use online cards for some things, but I do have my own "budget" system using bunq and therefore I have used my travel card to some online systems. As far as I understood you only have 5 online passes, which I already use 3 of them for stuff (because it makes my budgets easier), so that's the reason actually.
I see the Travel Card as a normal mastercard, I don't have that other debit card, that's also a reason I used the Travel Card alot.