I didn't say it was an agreed-upon scenario by the players - I said "let's say your group is playing Keep on the Borderlands", but you've just automatically assumed I was talking about a scenario where the party knows what they are playing. What if they just sat down to a game and it happened to be Keep on the Borderlands (perhaps the DM wished to surprise the players, or perhaps he's playing with a group that knows nothing about KotB)? Your argument again comes from the meta-knowledge only a DM is meant to have, not what the players actually experience.
I did assume that, because asking players to play a preordained path without warning or conversation isn't a good thing to do in and of itself, and I assumed you'd agree with that. Players deserve to know what they're getting into, the dm deserves to know what the players might want beforehand, and games are consistently just better when those conversations take place.
Here's the thing, your claim is that the knowledge is something only DMs are supposed to have.
This is the first reason why I don't think I'd enjoy playing at your table. You don't seem to think that players are clever enough to see through the bullshit, and notice a railroad or an obfuscation or a premade piece of module, or otherwise recognize a scripted outcome.
Because you don't resolve book actions with dice rolls and rules. You don't develop characters in books. D&D is a game. The comparison is way off base.
It would be off base if the initial assumption was that dice rolls and rules mattered, but they don't if the DM will just do what they want to anyway. The comparison was made to contrast the two, and you've made my point for me. You don't actually resolve anything with dice rolls and rules, if the resolution is the same either way.
Here's my point, and a CYOA book is perfect for illustrating it: if you choose to go left, turn to page 7, if you go right turn to page 8. You have a choice - left or right. Choosing between left or right doesn't change what's on pages 7 and 8 - the outcomes are preordained, but because you have no idea what will happen, then you are still surprised by the result. The effect is that you feel as though your choices mattered, when really you won't know what was on page 7 if you went to 8 instead, and so if 7 and 8 were the same (which they may or may not be), you wouldn't know, essentially making it a moot argument.
First, you assume again that "you wouldn't know". Don't underestimate your players my dude, or your ability to let something slip.
Second, the argument is that if the same text is on page 8 as on page 7, or if both page 8 and 7 lead to page 12, or if no matter what pages you choose, you end at page 110 all the same, than you had no real choice but that you chose a railroad to ride on, but not the resolution or the outcome.
You've claimed several times that your game is 100% improvised, but simultaneously claim that you reserve the right to drop in premade things and to use predecided upon ideas that the players previously avoided or in some other way without regard for the players choices throughout the session. YOU are choosing the resolution of the gameplay- not the dice, the rules, or the players.
That isn't 100% improvised by the definition everyone else here would use, so we're all a little confused I think.
I don't mind the idea, per se, of having floating elements that you maybe use later on if they simply didn't come up. But I do mind the attitude that you'll use them even if the players, using the dice and rules, opt out. No DMs ideas are so good that they deserve to see play, no matter how the players avoid them.
The second reason I'd likely not enjoy your game is the seeming unwillingness to take the red editors pen to your ideas and kill your darlings.
Your entire argument, quite literally, comes down to this: it isn't railroading if you get away with it.
There is firstly a problem if a DM is trying to get away with something instead of just playing the game.
There is secondly a problem if the DM believes he can get away with it at all, unceasingly, in the face of however many players are at your table.
You continue to argue as well that we shouldn't be arguing over things the player may never see, and asking us to "stop arguing the merits of a player facing interface". To which it seems most of us have blatantly said, "no sir, thank you", because it is an important stance and because for my own part my players deserve to have their perspective considered and not taken for granted.
Frankly, when you approach DMing with the mindset you seem to have, I feel it doesn't support or foster a great game for everyone involved. Only what the DM thinks is great.
You claim that we are seemingly incapable of seeing through the eyes of the player in the moment, but that is in fact literally what we're doing. And I counter-argue that you appear to be incapable of accepting that we may just quite simply not want to pull one over on our players like that, even if they never knew and that I, at least, feel that it does affect the game in a negative way to do so.
So, in point of fact, I think you underestimate your players, I think you may be unwilling to let your brilliant ideas die, and I think you're too willing to ask multiple other DMs to not tell you we think you're view of the players perspective is incorrect.
All three of these points are red flags for me, and so I would avoid your table. Don't take it too personally, I'm not trying to attack you as a moral entity, it's simply a potentially incorrect viewpoint. But I hope you consider that maybe at least your players might be more clever than that.