This video is a great representation of how I felt about Red Dead Redemption II, but the video author went even deeper than I did into the systems, finding issues. Here's a shorter version than that 40 minute video.

The single player story missions don't actually let you use all of the open world systems they crafted to resolve your missions. They have one specific idea for how the mission should be completed, and anything outside of that is a fail state. One specific instance from my own playthrough was that I had to sneak into a factory's second floor. I snuck around in the dark and found a way to climb onto the 1st-level roof so that I could open the window and get into the boss's office that way. Mission failed. What they wanted me to do was go through the first floor and walk up the stairs for some reason instead of the solution I came up with. If they really didn't want me to go in that way, they could have blocked the window with an obstruction or something, but instead they just gave me a hard fail state. The whole game's story mode ended up feeling like a giant tutorial, so on-rails that they don't want you to do anything but one the thing they're trying to teach you; except you run out of stuff to learn in the early parts of Act 2, so it just ends up being really frustrating when you don't read the developers' minds and solve it their way.

As for the story playing out exactly the same way, that's not at odds with what I wanted. At the end of each Act, there's a big job, something goes wrong, and you have to move to a new camp. None of the missions between those events would prevent it from happening. They can still have their big set piece moments and keep those missions exactly the same. But what they could have done, that would fit the narrative they built perfectly, is to let me earn money however the hell I want, which is an idea the video author had as well. Again, the game itself is what set our expectations for this to work. It's a game that allows you to earn bounty money and sell skins if you want to go legit, and it lets you rob trains and banks if you want to be an outlaw; except not really on that last part. Train and bank robberies are basically scripted events only (and they always go wrong instead of ever allowing you the satisfaction of a well-planned heist, like a good open world game in this setting would). And despite the story constantly revolving around getting more money, they don't give you a threshold of money to reach that allows the story to move forward. It only moves forward after you've done all of their missions, and the money doesn't really matter at all. And this is a huge missed opportunity, because it would encourage you to engage with all of those open world systems that their missions don't actually let you use.

If you want to see a perfect example of this money mechanic already implemented in another game, look at Baldur's Gate II. The early hours of the game give you a simple objective, rescue your sister, and there are three obvious ways that the game presents to you as to how to do it, one of which is to raise like 20k gold. How you get that gold is up to you, or you can also just enlist some nebulous factions to get you the info you need for a favor instead. This objective encourages you to do whatever side quests you find interesting, since most of them pay you money. This structure would have been right at home in RDR2.

GTA V's idea of freedom, which is still better than RDR2 but worse than a lot of modern sandbox games, is to give you like 3 options for any given heist, and you do setup missions for them. That's cool, but it would be nice if they expanded on this to give you less explicit options and more systemic ones. Like maybe one option is to break through a gate, and you could do that with explosives, an armored car, or a 737, if you hijacked one earlier.

NakeyJakey explains it well I think

His example of GTA III having a mission where you can pre-plan by installing an ignition explosive on a car before a mission and then use that explosive to insta-complete a mission is a great example of old rockstar design openness with missions

Compared to RDR2 where some missions will fail you for going slightly off the beaten path even if it's not out of character or a bad time in the narrative to do so, or break if you do something cleverer than R* expected you to be

I ran into few moments where I tried to take an alternative route to take down enemies, and game deciding I had strayed too far and failing me. Game wanted me to just go straight at targets. Had timed where I did go straight ahead but I was going faster than the AI companion and got failed.