Slippery slope has almost always meant a fallacy, because it typically invokes "the sky is falling" examples that have no evidence to support it coming to pass - even here.
While I see the point, "slippery slope is a fallacy" seems to have been abused far more than "slippery slope" on HN over the decade I've hung around here.
That's because nobody makes an argument by starting with "I'm making a slippery slope argument" - it's always identified by someone else. Same with whataboutism, no true scotsman, etc. by their nature.
No, it is because people invoke slippery slope fallacy for actual, real slippery slopes.
The slippery slope fallacy us real - but so are the slippery slopes.