I think the most tragic part about NPR's decline is that they veered so far into activism, they often don't bother presenting the other side of contentious issues. As another commenter pointed out, NPR covered a variety of perspectives on the American War on Terror. That seems to happen less often nowadays.
News orgs are not obligated to present sides of issues as though they're equivalent. Just because a point of view is prevalent doesn't mean it's valid. But as I've pointed elsewhere in the thread, On the Media handles controversial topics better than anyone. They are exceptionally good and digging in to even the most conspiracy-laden topics with clarity and fairness.
Consider the most recent geopolitical conflict involving the US, the war in Ukraine. There are a number of articles on NPR's website about the possibility of the US sending F-16 jets to Ukraine.
I've read many of them, and they tend to support the US sending planes. Some of these articles include quotes from Ukrainian defense officials who are obviously in favor. Some articles speculate as to why the US has not done so (e.g. the overhead of training pilots).
My issue with the reporting is that the writers never really bothered to explain the arguments from the opposing side. Obviously, this decision involves many tradeoffs and it was not taken lightly. NPR's reporting on this subject was not very informative and it just left me asking more questions. As a reader, I want to understand the tradeoffs behind important decisions.
This isn't the only topic with shoddy reporting. It's just the first one I noticed where activism got in the way of journalism. There are legitimate arguments in support of both sides of this issue (and I say this as a supporter of Ukraine). Readers are entitled to read/hear them, and writers should present them fairly.