I was really only joking about Doctor Who, but that brings us back to the original topic. I'm pretty sure that any 10 year D&D campaign is not going to be based around a single storyline from start to finish. But you might drop in shorter adventures, as episodes.
My DW game has had a core thread (one the players have learned much about) for six years, admittedly counting a number of breaks.
Someone else mentioned session zero earlier so I'll ask the never asked questions. How could any of these problems have possibly happened if you beat the bolded drum loud and proud during session zero while sending off fireworks to accompany the red flags you were waving for all to see like how you expect immunity to PC death no matter your actions and choices as a powerless puppet of chance?
And, yet again, you put words in my mouth and talk down to me rather than being respectful and earnest. I genuinely don't know why I bother sometimes.
But I did raise my concerns, in both of the games mentioned. I did so tactfully and only once in public (because I did not wish to be That Guy), and then reiterated them to the DM multiple times thereafter, trying each time to be clear, specific, respectful, and demonstrative. Both DMs blithely ignored everything I said. One on the basis that his
other group he was running things for was doing just fine and had never even had a particularly difficult combat no matter what he chose to throw at them, so
obviously our party would be just fine too, I was just a worrywart, everything would be fine. The other because the game had been so short thus far, the DM believed I was jumping at shadows and drawing unwarranted conclusions.
We had session 0 in both games. Both were pretty brief and perfunctory, almost totally spent on answering character creation questions, but I asked whatever questions I could think of to be helpful for the brand-new players who wouldn't know what to ask. Neither DM ever once mentioned things like "be careful where you take short rests, you might be jumped by bandits." No NPC ever mentioned anything like this, and indeed before the bandits showed up in the first such game, I wasn't even aware that there was a bandit problem. We were in ruins only a couple hours' walk outside of town for God's sake, and arrived in broad daylight.
Did you not do anything like that because the gm didn't think to explicitly ask those specific questions?
I did a great deal in both cases. These DMs failed to even partially meet me halfway. For one of them, it wasn't their first campaign, but I don't think it was even their fourth, so I was trying very hard to respect their boundaries and not overstep my position, as I was by far the most experienced player at the table. I gave advice and comments. I kept most of them private between the two of us, because I did not wish to be seen as badmouthing or disrespectful, and instead wanted to set a good example to others for how I feel a player should act toward their DM. (Namely, speak up for yourself, but do not be disruptive; if you dispute a call, make your case and push for your views for at most a few minutes. Don't turn the session into an argument, friendly or otherwise. The time for serious discussion like that is between sessions.)
For the other, I would generally have called them an experienced but not necessarily "long-time" DM, if that makes sense, and thus I presumed, I guess erroneously, that they knew what they were doing. Since I didn't actually know anyone in that group beforehand, I could not rely on friendships or common ground to make appeals, so I strove extra hard to be circumspect about my comments and concerns. That game
did have a session zero, but the DM must have badly flubbed their explanations, because nothing at all they said about it gave the impression of "this will be brutally hard, very slow, OSR style play." IIRC, they even claimed it would be "lighthearted" adventuring. That game failed by the end of the third session (with, as noted, a full TPK).
I was very specific about my concerns over how fragile characters are at first level and, when we went more than two sessions still at that level, how risky it was. I was ignored, and the results panned out exactly as I feared, despite my best efforts. Ever since, I have endeavored to comment more vociferously (in private, of course) upon how fragile first level characters are in 5e. At best, this was again blithely ignored. Most of the time, two to three years ago when I was to some degree actively looking for a game, it was met with an immediate "are you
questioning me?" response, which has always made me run for the hills. That was one part of why I had such a difficult time finding any groups willing to play anything remotely like my interests.* Because literally saying, "Do we need to start at first level? I find it extremely fragile and have seen this harm or even ruin multiple campaigns in the past" is apparently enough to raise 5e DM hackles and bring out the subtle-threat language.
*Thankfully, Hussar has very kindly offered me a place at his table, and it is a treat. Even if I'm a dingus who forgets what day it's on.