I don't disagree but the reason why P players say this is because so many non-P players talk about how non-versatile the P bass is. How it has no low end and therefore shouldn't have been used live by Dave Holland, etc. How they sold their P bass and bought a Jazz because the P just wasn't versatile enough, because it only has one pickup and passive electronics. I've heard it all, and the situation you described with a hypothetical trumpet player actually fit the P bass analogy really well: one simple horn, many styles. The reason you don't hear trumpet players go on about it is because no one is bitching about how their trumpet only has three keys and no pickups, and no one is telling trumpet players that their horn sucks because it only has three keys and no pickups.
However, *every* instrument has gear sluts... Even the trumpet. And every instrument has gear snobs - On TB I've seen SX players poo-poo everything from Jay Turser basses to Sadowsky's, so the snobbery is by no means limited to the boutique bandwagon or the Fender bandwagon or the Precision bandwagon Jazz bandwagon or the Lakland bandwagon. Extended range versus what Jaco used. Relic versus pristine. Vintage versus brand new. When we talk strings, we get the same BS between flats and rounds, and when we talk amps we get the same BS between tubes/solid state/hybrid/class D, weight, Ampeg, Markbass, GK, Fearful, combos of doom/810s, ad nauseum.
I got sick of this on TB and stopped being a supporting member. Then I stopped reading for many months. I peeked back a couple of weeks ago out of curiosity, and it's the same BS.
My Fender P is awesome. It's the sixth or seventh one I've owned, and I love it. I've also owned a couple of Jazz basses, Squiers, MIM, etc. and played a Peavey Patriot almost exclusively for 22 years. I've played many others. I've owned several Traynors, Peaveys, a GK, a couple of Markbass amps and gigged many others including Fender, Ampeg, and straight to the board. I've played rounds, then flats, then rounds, then flats, then rounds on some basses and flats on others and am currently flats on my only two remaining basses. I've boosted bass, boosted mids, gone flat, dialed in contour and presence and dialed it out. Wanna know a secret? Outside of the small musician subculture, all of the differences are moot because NOBODY CARES!! To any non-musician (except spouses and girlfriends) they ALL SOUND THE SAME! And even to many musicians! Including bass players!! Get over it!
Where's the Tylenol???