This seems to me a reasonable question (at least partly - see below). To be clear, I said that reading the work of experts is more likely to produce a good understanding than merely writing-up one's own thoughts. My answer:

For any given field, reading the thoughts of experts -ie, smart people who have devoted substantial time and effort to thinking and collaborating in the field- is more likely to result in a good understanding of the field's issues than furrowing one's brow and typing away in relative isolation. I take this to be common sense, but please say if you need some substantiation. The conclusion about philosophy follows by universal instantiation.

"Ah", I hear you say, "but philosophy does not fit this pattern, because the people who do it aren't smart. They're all at best of mediocre intelligence." (is there another explanation of the poor understanding you refer to?). From what I've seen on LW, this position will be inferred to from a bad experience or two with philosophy profs , or perhaps on the grounds that no smart person would elect to study such a diseased subject.

Two rejoinders:

i) Suppose it were true that only second rate thinkers do philosophy. It would be still the case that with a large number of people discussing the issues over many years, there'd be a good chance something worth knowing -if there's anything to know- would emerge. It wouldn't be obvious that the rational course is to ignore it, if interested in the issues.

ii) It's obviously false (hence the 'partly' above). Just try reading the work of Timothy Williamson or David Lewis or Crispin Wright or W.V.O. Quine or Hilary Putnam or Donald Davidson or George Boolos or any of a huge number of other writers, and then making a rational case that the leading thinkers of philosophy are second-rate intellects. I think this is sufficiently obvious that the failure to see it suggests not merely oversight but bias.

Philosophical progress may tend to take the form just of increasingly nuanced understandings of its problems' parameters rather than clear resolutions of them, and so may not seem worth doing, to some. I don't know whether I'd argue with someone who thinks this, but I would suggest if one thinks it, one shouldn't be claiming it even while expounding a philosophical theory.