1) I haven't been in DC in a decade sans a quick trip in 2011 to escort my brother to some college visits. I've been in Washington in and near Seattle since 2011.Politics only works that way in the tiny DC and DC adjacent communities you work in. Most actual political strategists rather than members of the DC failson class understand that to get the party closer to you to do what you want you have to be organized and willing to deny them your support if they don’t meet your demands. That is how the Koch’s built the Tea Party, how Reagan took over the Republican Party, etc. Your strategy is the pure idiocy of the dem consultant class that has been invented to soothe their consciences as they suck blue dog dick.
2) This isn't just DC, this is how electoral politics works all over the country. The loudest supporters tend to get the most attention to their issues because politicians want to keep them content. You can actually see that right now with city counsels acquiescing to some of the easier demands (some statutes and monuments) and starting on harder ones. Noise isn't enough, but if politicians think they're siding with popular opinion (even when they may actually be wrong), then they're more likely to push through or act on items that are "top of mind." Shit takes time and political capital, but being loud and giving the impression is a low-political cost item can get your policy towards the top of the agenda.
For now, but nothing is louder in politics than electoral results. If you can deliver a win, you can push an agenda.Protesters seem pretty loud to me.