Jargon is used in closed groups to quickly communicate information using a known set of accepted phrases, codes, etc.
In the day I served, it was all about acronyms, ABC this DEF that. As it got worse there were multiple meanings which only context would sort out.
Considering weapons, yeah, military grade weapons are platforms. HK did it first expanding the range of options to the point it was almost a joke, it seemed they were trying too hard to pay for the tooling. You could get a major or intermediate caliber HK in a range from submachine gun to bipod mounted heavy squad weapon or sniper grade rifle - and it seemed it was all just rearranging parts out off the shelf.
Just like the SOPMOD poster - and many don't realize it only showed a portion of what became available due to it's early release. Most of those gun closet papers tacked up next to some honey with nothing but curves to sell never include the CQBR upper, the 10.5" barrel which became the MK18 and which is the hottest weapon going for military use by "certain small units."
So, platform away. I first built an AR15 as a dissipator, then converted it to a 3Gun stripper to lighten it up for deer hunting. I'm building a AR pistol on another platform with parts off the first build, in a different caliber, same purpose and likely another pound lighter.
To me, a platform requires more than one version in service, the AR qualifies as 20" issue and DMR's exist, 14.5" is standard with the M4, and the MK18 comes in 10.5". They take all the same accessories and mags, what's not to like?
Beats having to order different scope mounts for the different rifles in the gun safe, nothing interchangeable. I work auto parts and hear a LOT of consumers complaining "why don't they make them all the same it would be so simple?"
We got that with the AR and we hear, "Why did they invent a platform that works so easy these things are everywhere I cant stand them."
I can legally swap my 16" 6.8 rifle upper onto my pistol lower and use the 6.8 mags hunting. (Don't even suggest what could be done with the leftovers.) That's a platform, same as the HK and SIG handguns that ship with 4 barrels in different calibers.
Nope, what we are really talking about are people spicing up their conversation by misusing jargon and catch phrases - and I heard a lot of that in the military, too. It was always done as a device to impress the unknowledgeable, which seemed to work most of time. I could catch it, but saying something would have only raised a big stink and brought out the rulers to see who was the Alpha Male.
If you see the jargon phrases from LEO psych work in that last paragraph no doubt you can contribute something to this thread, too.
In their context words and phrases make communication richer and impart more knowledge more quickly. Used abusively it's all about being a poser. Simple as that.