I don’t know their rationale but I think it may have something to do with whether the state’s real estate tax rolls are open for payment. IOW, they may take the stance you cannot pay ahead for a tax that is not due.
With the standard deduction set at 24K, one would have to have a lot of real estate tax, contributions, medical, and income taxes to be worried about this and also have to consider the tax bracket rates will be lower too.
Since auditing such a thing would be a nightmare, they may only take on the most egregious of the deduction scams. The selection program would have to examine whether itemized deductions jumped between TY 16 and TY17. Frankly were I making the call, I would not worry about it and just leave it to be picked up in the random audits done each year.
When I was concerned about deductions, the mortgage interest alone for me was around 24K. And I was single. But I don’t have worry about it anymore, as I moved to Texas. :-)