Maybe I have a mistake in my reasoning, and I'm going to get really abstract, but here goes:
I'm skeptical that "faithfully reflecting the spectrum of beliefs held by constituents" is a good thing. Not, at least, without some important caveats. Because faithful reflection, in certain contexts, can mean Jim Crow laws or other bare discrimination and immoral laws.
It's not a conscious thought, but I think the way you spoke of this also supposes that somehow, each person has a set of "Platonic political beliefs", as in, each person has a list of things they believe, and that with the right political infrastructure on top of people, we could tap into the "pure beliefs" and get out the best result. I don't really think people work that way: there are large and serious propaganda efforts that do actually have an impact on people's beliefs, and any political system which can't account for this won't work.
For instance, imagine a close senate race in a very properly Democratic state, but Russian targeted propaganda hit a few areas that actually swung the vote to the other side. During the moment of the election, that result accurately reflects the views of the people. Would it be fair to say that's a "faithful reflection"? In a naive sense, yes, but I think we'd agree no, that people's exact beliefs can be tempered in various ways, and that matters.
But enough abstract stuff, let's try to bring this concrete. When you say "Doug Jones represents the people of Alabama", my response is: what exactly do you mean by that? It's not at all clear that it's okay for him to be pro-life, representing Alabama, if the reason Alabama is majority pro-life is the result of the pernicious effort of Evangelical loons spreading propaganda and disinformation to confuse people about the discussion, and there's also the plain truth that most Southern red states are voter suppression states.
That being said, I have no problem with Doug Jones and am super relieved he won over Roy Moore. I'm just being typically postmodern-skeptic towards that framing of "belief" as something which can be accurately represented by democracy, or particularly how much such an idea stays coherent beyond a first approximation.
Oh, absolutely, no disagreements at all, in the grand scheme of things I'd take a Hillary presidency over a Trump presidency, even if that means compromising on political goals. However I'd still like those political goals
Lol I meant that rhetorically, that the Democrat's goal is to lose until the Republicans look so bad they can win. It was a joke about how the "gains" actually aren't a result of any level of.. frankly politics, but simply due to how awful the Republicans are.
Oh, I agree absolutely about ideological purity, and I think they should absolutely do what they can to win seats and kick Republicans out, any, all, especially the Paul Ryans in congress. I'm just worried they're going to take this short term advantage but not pivot into a long-term policy program that maintains support and helps stabilize the country long term, but they'll go for basically what they wanted with Hillary, which will only teeter the totter back and allow grievances to fester.