Because paying your advance tax will be seen as a normal expense as per your card data. So I'm guessing this may get flagged. To put things into perspective let's say your income is 50L. Your tax liability would be around 14L and it will be reported since this is more than 10L. The person in question here claims to be having tax liability in multitudes of lakhs. I personally invest the majority of my income. So 25L invested. So out of 36L, you should be left with 9L. But at first glance, the IT dept will add your credit card expenditure(technically tax payments) and your investments and find some discrepancies. This is not something to fret about, and can easily be clarified.
PS- What I said in my earlier post was obviously a hyperbole! But hope this explains my silly premise.