Rejected. The others pretty much summed it up, but the key thing to me is the extent to which this breaks existing levels, often in the "subtle backroutes are introduced" way (compared to "they don't work", "existing replays break" or "very obvious backroutes might be introduced, but nothing subtle" which I consider at least a bit more tolerable).
However, I will state that the above is not a concern if a new skill can be assigned to a blocker. As long as the difference from other skills can be justified, I'm quite happy for a new skill to be able to - because this doesn't affect existing content in any way.