Where's the evidence they do harm? Do we have something that shows that these attempts overall tend to stop further thought rather than start it? Personally I'd have thought that others coming across philosopher's conclusions are often sparked to either disagree or to attempt to prove it, and both of these can help knowledge grow. Alternatively, philosophers can suggest ways of thinking about things which can then be used productively.
Where's the evidence they do harm? Do we have something that shows that these attempts overall tend to stop further thought rather than start it?
I'm going to follow my own advice to philosophers and refrain from attempting to definitively answer your excellent questions. Instead I will limit myself to adding to your list of possible answers. I will simply mention the standard hagiographies surrounding Galileo and Copernicus and the negative roles assigned to Aristotle and other Greek philosophers and geometers in those stories.
But even though I sidest...
I've often wished for a list of cases where philosophy has proven useful, or has at least anticipated science in drawing correct conclusions. Here's one for the list:
The June 18 2010 Science has two very similar articles on how rat brains represent space. Both conclude that the brain already represents space as a grid before rat pups take their first steps into the world. Both make the point that this validates Kant's claim that space is an innate concept prior to experience.
(The next task is to make a corresponding list of cases where philosophers made incorrect conclusions; and estimate whether the number of correct conclusions is greater than chance.)