When someone with a PhD in philosophy is per se blacklisted regarding other matters of worldly concern, credentialism has gone too far.
To become credentialed in a field, you must spend multiple years repeating the same things over and over, getting programmed to perceive and approach problems in compliance with the field's orthodoxy.
There is a small core of people who decide whether you will gain your credential or not. These persons generally have interests besides just "train the best new $OUR_FIELDers out there", if only because that's subjective and will take many years to play out. They're generally looking for funding, projects, publications, appointments, etc. In charge of those people is university administration, and their conflict of interest is so obvious and inherent that it's a waste of time to type it out.
So you have this big powerful apparatus that has many little gullets that can be made to respond much more favorably by pouring a little money here, a little prestige there, etc. Many of these "gullets" will balk if this is done openly, but if you add a thin layer of abstraction and ambiguity, very few people will even notice the relationship, let alone care. It really only takes a minimal amount of obfuscation to get people to jump on board with something that has direct personal benefit to offer.
As such, the perspective of intelligent outsiders who haven't gone through an elaborate niche-specific brainwashing process should be valued, not dismissed.
What are your credentials?
Society encourages everyone to draw simple, binary boxes around people, but people are more complicated than that.
That PhD in philosophy is likely to give an otherwise naive person the useful information of, "yes, seemingly nice people will act like this if it benefits them, or if they've deferred to some authority that requires it of them". It'll also give a grounding in 'rationalizing such decisions'.
Wow that is an extremely subtle distinction.