You're being downvoted because there's a certain passive-aggressive subset who'd rather take the easy way out and just suppress an opinion they disagree with by pushing it into graytext territory than attempt to do the constructive thing and type out a thoughtful response to it.

Anyway, you're correct that slippery slope arguments aren't necessarily fallacious. A well-crafted one which demonstrates that sliding down the slope is inevitable can be quite compelling. One that I've always thought was particularly impressive is the line of reasoning that the political philosopher Robert Nozick employed in his book Anarchy, State, and Utopia to argue that an anarchist political system would not be viable.

Maybe it's just me, but I feel like people are increasingly using phrases that put wikipedia in the 'source' category.