Because it's 'replay', people somehow think that stopping time lets us see all with no subjectivity. Except that's just not true most of the time. So the replay guys ends up making an over-thought, intellectually biased decision on an inconclusive replay, which IMO is far worse than a ref making a split second call on the spot (when he's only thinking about the call and not the teams, the game situation, etc).
It is the absolute worst thing about sports. Expanding reply to PI penalties will be a horrible.
It's hard to even fathom how random and capricious that rule will be implemented. Prepare to be infuriated Bills fans.