So I have been thinking hard about the question of whether it's possible to have a time skip or hand wave that is not an act of railroading, and I do think that I have a scenario where it wouldn't be.
The GM accepts the intention to handwave away an event or time skip over something knowing that he was looking forward to that event and considered it important. For example, if the GM had prepared a fight to save a caravan from orc bandits and some important NPCs he wanted to introduce, and the party said, "We want to just skip over the travel.", if the GM deliberately cancelled his own plans then we could reasonably suggest we could know he wasn't acting in his own interest or out of his own bias.
I'm not sure that this is a very realistic scenario. I suspect that for the most part it never occurs to a GM to time skip over a prepared important event (that is important as he understands it) that he spent time and thought on. But if they did just throw away their plans for whatever reason, that wouldn't be a railroad.
Wait wait wait wait wait.
So, now it's not, even remotely, about any form of agency at all--even though that's pretty consistently what
everyone else uses the term for--and is instead solely and exclusively about GM
caring about the content being undertaken or skipped?
Absolutely the heck not. Like how do you even start from this as a base? What? Seriously? You're literally making it so if the GM
cares about their campaign, in any way whatsoever, that automatically means EVERYTHING they do is railroading. Seriously? You've turned the term into something totally useless!
And, more to the point,
I have done exactly this with my own game. Not exactly in the sense of "caravan skipping past orc bandits", but I prepared--with rather a lot of detail--a "boss fight" of sorts near the end of a druid sanctuary the players came to call the Charred Marsh Grotto (since it had been set on fire and they'd put out the fire before entering). The players, through exploiting a loophole I hadn't considered, completely demolished the monster without making a single attack roll. They just baited it into one of the traps, which (functionally) deleted it. And I absolutely let that stand, because the players earned it, fair and square. I
do think it would have been more satisfying and exciting to do the fight I'd planned, but I consider it utterly unacceptable to intrude on the players' efforts in that way...so I won't do that. Ever.
And yes, I
have spoken about this on this forum many, many times before, so it's not like I'm inventing this story off the cuff. This was specifically the "molten obsidian golem" fight. I'm sure if you look up the words obsidian golem on this forum, you'll find posts I've made about it.
So, by your own lights, I'm apparently a GM who specifically doesn't railroad, even with your nonsense "if the GM cares about it, then it happening is always ramming the players through a railroad" definition. Something you've claimed should be impossible.
Edit:
In fact, I can do one better, I have another example of a time where the players made a choice which
hurt them in a way that pre-empted my efforts at creating an exciting and interesting encounter. In this case, they had captured a low-level gang leader (think "head of a squad of ganbangers" level--the equivalent of a local cell leader in a terrorist organization). Said gang-leader was supremely confident during questioning, which the players correctly concluded meant that he thought he would be sprung by the gang. So, the players intentionally
allowed the prison break to happen on their watch, and took steps to be able to
follow the ganger back to whatever place he was going to report to. Letting the little fish go in order to catch a bigger fish, which was a smart move!
They would have succeeded....except that as part of their efforts to track the guy, they trusted someone they shouldn't have, who doesn't actually
know that the person
he reports to has connections to the gang. As a result, the gang intentionally cut back their presence to the bare minimum necessary to not give away that they'd known about it, and the underboss had already fled, leaving an illusion of himself behind so he could see and speak, but not be touched nor followed. I
had been preparing a grand heist with lots of challenges to work through before reaching the underboss, and then a big (under)boss fight to cap it off where they'd have to try to
hold back enough to capture the guy alive, rather than killing him, since capturing him alive was the whole goal.
But because they made that one unfortunate mistake, nixed--losing them both the beneficial thing,
and a result I personally had been more invested in and thought would be more exciting and entertaining. I didn't prevent them from making that mistake, and I didn't tell them about it until they discovered that their plans had been ruined, because they would have had no way of knowing that their trust was misplaced, the guy they've been working with has been genuinely good to them, and they couldn't possibly know that his superiors work with the gang since
he himself doesn't know.