I do things biased on what my players want. I know that several of them want to have these epic character narratives, while a few of them are just along for the ride. For those players that've build narratives for and with, I create plot points that will always happen. If character X's whole motivation is to avenge their fathers death, they are inevitably going to run into the person who killed their father. However the path between point a and b is winding and massively variable.

For example, I very heavily implied that my group should go to a certain location for the main story. All of the NPCs were going to this place, and the party should too. They didn't. They went to the other side of the world and I built an entirely different story for them, that lasted an IRL year with weekly play sessions. However, one of the player characters had some important stuff that needed to happen, so I made sure to put the situation that would allow for that characters story to happen in the new location, despite it not originally being there.

However, if the table is having fun, and if the DM can maintain the illusion, then I suppose that none of those problems are problems for them. Truth be told, some tables don’t care about a sandbox experience nearly as much as others. Some just want to drink beer and roll dice. Some want a more plot-centric storyline, which by default requires a certain degree of railroading to maintain. Different strokes for different folks.

Yup... my group specifically rejected a campaign that was a complete sandbox and open-ended, and asked for a more DM-driven storyline. They chose that option as a group. And when I asked them if they wanted to set their own milestones for gaining XP, they said no, you do it. So my group wants more "GM Direction" than some groups.