Some people really are going into a rude awakening about the limitations of the presidency as well as the rules of Congress and the courts.
Although I'm starting to wonder if a term of failed promises is what's needed for pragmatism to once again take hold.
It seems that you're the one who doesn't understand how it works. You vote on candidates' vision / ideals / ideal policies that those candidates want to bring forth. You can't expect candidates to bring forth the exact policies that will be accepted by the country at large, because the compromising and negotiation is what happens afterward. What you're asking for is for them to do the negotiations by themselves, beforehand? How does that make any sense? Do you haggle for prices by starting with the exact amount of what you think they'll go for, or do you start by asking for more than you even want?
Not to mention the fact that virtually all politicians are outright liars most of the time, and will say anything just to get elected. In order to discern between people you need to see how genuine they are, see if they trip up and get caught in lies etc..
What you're calling "pragmatism" is both closing yourself off for potentially more, as well as cutting off a good chunk of information to discern if politicians are in good faith or not.
But then again, with arguments like yours, I don't believe it's in good faith to be honest. I can't believe that anyone who would
want the things that Warren and Sanders want, could ever consciously choose to
not vote for the people who also want that. Why would you ever do that? I don't get it. Even if you think you'll end up at the same point eventually, why would you want to cut off the possibility of getting closer to what you actually want? I don't believe that you want the same, but if you do, then I'd like to go in a bit deeper on that, because it's quite a sad thing to see if it's true to be honest.