Maybe those people are bad at "tabooing" their topics. Which may either mean the topic is very difficult to "taboo", or that they simply do not think this way and instead e.g. try to associate the topic with applause lights. In other words, either the "philosophical" topics are those where tabooing is difficult, or the "philosophers" are people who are bad at tabooing.

Since there are many different philosophers trying many different things, I would guess that it really is difficult to taboo those topics. (Which does not exclude the possibility that most philosophers are actually bad at tabooing; I just think it is unlikely that all of them are.)

On the other hand, maybe the philosophers who taboo the topic properly are simply ignored by the others. The problem is never solved because even when someone solves it, others do not accept the solution.

Also, even proper tabooing does not answer the question immediately. Even if you taboo "knowledge" properly, the explanation may require some knowledge about informatics or neuroscience, which may be not available yet.