I have stopped regarding it as a fallacy. It seems to be something of a predictive measure at this point.

It's a fallacy to say that with a "slope" of states A B and C, with C implying B has been reached, that moving from A to B means you'll necessarily go to C next. The fallacy doesn't mean we can't go from B to C or that it isn't easier to get to C from B than A.

Which is why it's called the "Slippery Slope," not the "Sheer Cliff" or the "Trap Door" or the "Gravity Well."

Whatever ancient neckbeard decided it was a fallacy clearly didn't get out much.

The slippery slope is a logical fallacy. But people aren't logical entities for the most part, and the real world doesn't even vaguely resemble a philosophy classroom.