Not enough to make the game a railroad game. It's hard not to know that you are forcing your vision on the players when you do it consistently. I will agree that they may not know it's called a railroad, but they know what they are doing.
It really isn't as hard as you think--especially when GMs in this very thread, self-professed "sandbox" GMs, are perfectly comfortable inserting "hooks" if they feel things have bogged down or the like.
It's much easier than you give credit for for a person to think what they are doing is right and productive when it isn't. I'm not saying you specifically, or indeed any specific person here, is doing that sort of thing. I'm just saying that it's really not that hard for a GM to fall into the mistaken set of beliefs and thus think what they're doing is the right or correct thing to do even if it isn't. Black-boxing significantly increases the risk of such a situation, because inside the black box, the only check is...yourself.
You didn't know that you were forcing your vision on them? I find that hard to believe. I do believe that you were directed to play that way. AD&D was like that. I also believe that you didn't know it was called railroading.
It is quite possible to have a too-fixed idea of what "railroading" means, and thus excuse behavior which actually is railroading as something else for a variety of reasons. Bad advice from people who meant well but who also misunderstood. Trying a technique, seeing that it seemed to work, and sticking with that technique even when maybe you shouldn't have. Excusing a technique because it's being used for the
best of reasons...even though what it actually does is force a particular outcome (e.g. fudging). Leaning too heavily into something you thought was a subtle signal from your players, and thus thinking you're "following" them when you're actually leading them. Genuinely being just inexperienced with sandboxes and trying to use the skills you already have outside their domain of applicability. Etc., etc., etc. There are all sorts of ways for a well-intentioned person, with the goal of avoiding railroading, to fail to meet that goal.
Particularly when we recognize that, just as there are degrees of sandboxing, there are degrees of railroading. So, for example, a DM might actually engage in some
light railroading sections here, under the belief that they aren't "truly" railroading and thus not a problem. Or having, as I've mentioned previously, some railroading baked into the setting material itself, where over time, because of how the setting is constructed, it
eventually ends up pushing the players in a particular direction because a problem or need takes over until addressed (which can be 100% "objective" and purely done by extrapolation from pre-written text, whether shown or unshown!)