If there is significant social pressure (either from the GM or the other players) to go along with the provided hooks I'm not sure if it's railroading, but it feels close enough for government work to me.
Adding to this - for me at least, and I'm going to guess for you also, we can draw meaningful distinctions between different bits of content, in terms of how they speak to us and how they sit in the "social pressure" dynamics.
When I think of a "hook", I think of the classic module starting point, where I as a player am expected to pick up on a bit of action or a clue that the GM presents that has no relevance to my character as I am conceiving of him/her
except because I as a player know that if my character doesn't pay attention to this then there will be no game. For me, what is most marked about this content is that I have no
internal or
character-grounded reason to care about it.
And the same is likely to be true as we go along the adventure.
I'll contrast that with the episode of play that I mentioned just upthread, involving the letters in Evard's Tower. Now someone might want to say
well, those letters are a hook too! But for me, at least, the difference goes pretty deep:
* The reason the action is even taking place in Evard's Tower is because I, playing Thurgon's sorcerer sidekick Aramina, who has a Belief about finding spellbooks, declared Isn't Evard's Tower nearby here? and then succeeded on the Great Masters-wise check. That was me - as per the instructions to BW players in the rulebook - deliberately seizing control of the fiction to push it in a direction that I wanted it to go in.
* I can't even recall now whether finding the letters was a success or a failure on Scavenging (all I can see is the record of making a Beginner's Luck Scavenging test marked on the appropriate part of my PC sheet). But the reason the GM narrated the existence of letters indicating a connection between Xanthippe (Thurgon's mother) and Thurgon is because I, Thurgon's player, put Xanthippe and her fate and the broader fate of Thurgon's family and ancestral estate front-and-centre (via the Relationship with Xanthippe; an Affiliation with the family; and the Belief about the future of the estate).
* Even the fact that there was a campfire to burn the letters in flowed from an Instinct that I wrote for Thurgon When camping, always ensure that the campfire is burning.
The social pressure is flowing from me as player to the GM. mediated by the game rules and principles, to
make all that stuff that I am the author of front-and-centre in play. It's completely different from turning up, spotting the GM's hook, and going along with it because that's today's adventure.
This is also why I am puzzled by
@EzekielRaiden's suggestion that a GM who frames scenes and introduces new content in this sort of way is railroading. To me, as a player, it feels the exact opposite.