I don't see why people care so much. Its just another echo chamber that can be completely ignored. Clearly the benefits of free flow of information outweigh the drawbacks so its best to just accept the drawbacks.
I filtered out /r/the_donald forever ago and I'm only reminded of it when a new anti-trump echo chamber spams its way to the top of /r/all. Now I have dozens of those filtered but its hard to keep up.
It's hardly a sandbox, but more of an inlet with a lot of spillover. There's anecdotally been a HUGE spike in bigotry and white supremacy on what used to be good subs since last year when that sub grew in numbers. Looking at the post history of these users, it almost always includes t_d.
They're also no strangers to organized brigading of other subs, unfortunately. It's a pretty irritating phenomenon.