What was wrong with the P-mount ?

It’s my first P-Mount @lewm
Looking at the catalog i think Technics P-mount 205 mk4 is standard ?
B&O looks different

I've only had one P-Mount Turntable/Arm — Technics SL-15. It took every P-Mount cartridge I tried, from Technics to ADC, Ortofon, Shure, Audio-Technica. As I understand it, the whole concept behind P-Mount was standardization and ease of use — any P-arm could take any P-cart on a plug-and-play basis — so the idea there'd be differences that rendered them incompatible makes little sense.

B&O did not make P-Mounts. Their own design of "plug-in" is not compatible with either standard or P-arms... which is unfortunate as B&O made some wonderful carts. Moreover, their plug-in designs kept changing, and their cartridges must be matched to the correct model TT/arm.

I can not comprehend, fathom, or understand why any serious audiophile would engage the use of a P-mount cartridge in a Music Reproduction System it is just a compromise offering no improvement, benefit, or advantage.

Technically, I suppose you are correct, bimasta. The term Pmount  probably should be reserved for that one kind of mount. The B&o mounts are different as I already said and you’ve reiterated. Fair enough.

I can not comprehend, fathom, or understand why any serious audiophile would engage the use of a P-mount cartridge in a Music Reproduction System it is just a compromise offering no improvement, benefit, or advantage.

The hype started with P-Mount cartridge made by Technics, it was the best cartridge from this brand. Actually it was made in two versions: P-Mount and Headshell Integrated. Audiogon is full of information and rave reviews about P-Mount version, you can easily find and read. Search for Technics p100c mk4 It was long time ago, but seems like people were crazy about this cartridge, it was MM. You can find statements like "the best MM ever made". Nobody cares that it was P-Mount, it was easy to use with P-Mount adapter like this.  

Another version of the same cartridge was headshell integrated. personally i like headshell integrated cartridges, i owned many Technics, these two were my favorite (before i have found much better cartridges). 

At that time almost everyone tried to say that P-Mount is better than headshell integrated version. People paid crazy amount of money to VdH who personally refurbished those overpriced P-Mount Technics p100c mk4 samples for audiogon members. 

Nowadays people still ready to invest over $2000 in this Technics Pmount p100c mk4 (if the condition is good). 

In the 80's Technics released mk4 version in 205 series.
The EPC-205c mk4 is so cute, i enjoyed it, this is where i tried and compared original, jico sas, axel's refurbished ... 

Because i like the design of the 205 series i bought my first P-Mount version of this red cartridge (P-205c mk4), don't know why, it was hard to resist, we will see if i'm lucky with the damper this time. 

Well, i was trying to say that the hype about P-Mount cartridge nowadays was just because of the Technics top models, they are simply not available in conventional version.