Why do we have to worry much about payload ? Tacomas as stated will carry much more weight than what some of you are thinking to have mods wise and they do so with a whimpy V6, i know i've had two

Hoping not to rub the dudes who are into towing and what not cause i swear that's not my idea.
I'm not into towing anything so ive never been inclined to think much about towing capacities. I know Payload is the max the manufacturer advertise for cargo, passengers, accessories, but isn't that for a vehicle with stock everything ? it can be calculated as GVWR - Curb weight. GWVR won't change cause it's hardcoded from the manufacturer in our doors jams, so we're toasted cause we can't increase that. My 4th gen crew cab 1500 for example has a whimpy 6900lbs GVWR., max factory payload from the sticker "The
combined weight of occupants and cargo should never exceed" 1484lbs in my case.
I've added 800lbs in mods so i can literally carry myself, (200lbs) and literally 2 more adults and my truck engine/trans will explode ? i carry more than that just going on a offroad camping trip by myself and the dog. My truck weights 6200 without me in it. (measured at public scale)
On another curious note the GAWR is 3900 front or rear, that will mean combined weight rating at the axels is 7800lbs. Why is the GVWR 900lbs less than the axel rating combined ?
I'm running E rated 315/70/17 tires, truck came with P rated 275/60/20's. P rated tires in 275/60/20 are rated at 2600lbs each at 35psi. i have more than that with E rated 315/70/17's, according to the TRA table they can hold 2685lbs at 40psi where i'm running them. So all combined the tires can hold 5370lbs at the axel.
I have better than stock brakes, 75% stiffer than stock rear springs with race shocks, race coilovers in the front with stiffer coil spring rates, truck has a HD trans cooler, electric steering has never complained in 94k miles even on 37's with the same weight mods. Have never seen anything abnormal out of the TC or diff fluids, changed every 30-40k miles. Trans has never ever overheated even in the longest inclines fully loaded with camping gear and all the crap we tend to carry around so we don't miss home.
The RAM is prob the first vehicle i've had where carrying more weight is so damn easy, no regear (i have factory 3.92's but the old 6 speed you guys with the 8 speed have it even easier ) no welding anything in the bed to add extra support for weight or offroad abuse, everything in the truck is HD at least compared to a Tacoma, i had 4.56's in my 1st Taco, 4.88's in the 2nd and that was just with 33's so what gives ? the Hemi has more than adequate tq to move payload plus say 400-500lbs more and that's even with 35's. Dang my Jeep JKU was almost as heavy as my RAM with the little Pentastar and 4.56's, that had steel HD everything for rock crawling. same story bigger rotors, heavy duty springs, better shocks, etc, trans cooler, etc etc.
So what's the issue with exceeding payload if you have a modded vehicle?, true question i'm not trying to be smartass or anything just in case. Honest question.