A slippery slope argument assumes the maximum degenerate outcome of sliding down the slope as a certainty, that no one will be able to correct for, mitigate or reverse the slide when it starts. That's what makes it a fallacy - it's a thought terminating cliche meant to eliminate the possibility of nuance, as any middle ground is implicitly part of the slope.
Otherwise, it's just an argument that risk exists, which is obvious and uninteresting.
Or if it's really bad, they make up entirely fanciful slopes that you could fall down.
Does it count as a slippery slope fallacy if the government argues that not stopping encrypted communications will result in terrorists killing your grandma? Because I heard that one a lot when Bush was president and they haven't really ever stopped using it. Is there a better fallacy for that example?
It's effective, because markets (including the marketplace of ideas) are irrational and bad faith tactics are often more effective at influencing people (at least in the short term) than reason and verifiable fact. I wouldn't consider it valid, though.
Otherwise, it's just an argument that risk exists, which is obvious and uninteresting.