I think it depends.
If the players accidently take some action that gets them off the path, and the GM steers them back onto the path through some kind of scene, then I don't view that as negative railroading behavior, although the overall game structure is still an accepted railroad.
If the players deliberately evade the storypath by ignoring the story hooks, then they're violating the social contract they took on by agreeing to play in a story path adventure. If the GM never offered them a choice and the players are rebelling by not following it, then we're just into wildly degenerate play.
The worst kind of railroading, the one we were warned about in the '80s and '90s, is the illusionary/deceptive railroad. The one where the setting presented is that of an open-ended sandbox, but the DM has actually embedded an entire story path in the game and expects the players to follow it. The classic "the mountains in the north are unclimbable, the desert to the south is uncrossable, and the ocean to the west is too stormy to sail, so I guess we'll go east."
That's the true pejorative of "railroading", the deception. Non-pejorative railroading is simply a game with an expected path and endpoint.