I did exactly this and today got the following reply from the ticket office:
So how do they suppose I get seats together with people who buy tickets across windows? I picked seats in the same block but by the time I could buy the second one the seats nearest to the first were 10 rows away.
When I bought multiple tickets in the same window for previous games they would always be together by default. So, other than helping those coordinate purchasing more than transaction limit, I'm not too sure what problem the seat map solves for this when it takes away the ticket office's ability to move seats together after purchase.