Someone please explain the logic of upgrades

Speaking of an upgraded 8k amp sounding very close to their 17k version: I give you the CJ5 vs the CJ8.Had the 5's for about 5 years and owned the 8's for 3 years.Meaning I owned both at the same time for 3 years.(Just sold the 5's)--System for most of that time was Audiomecca dac. CAT3 for pre. Synergetic active X box.and Montana EPS with Celtic Silver to the speakers. Lots of big buck cords--2 king Cobras---2 AudioMagic Stealth conditioners.---I had some big buck cryoed tubes.
I swear I could take the best tubes;stick them the 5's-- yup,right up there with the 8s.
On to why the amps don't come with the best,whatever feet or cords---- Amp mfg's put their resources on the inside.--I guess Carma might be the exception.

I was drafting up a lengthy response rejecting your learned opinions and opining that manufacturers should use only the highest quality parts, thus eliminating the need for any future upgrades. But, I suddenly realized that, had AI done that, I probably couldn't have afforded their preamp on my meager budget. So I'll drop the issue.

Bigtee - what's tube rolling?

Tube rolling is simply trying different brands of tubes to change the sound from the tubes that came with the gear.

Hate to go here - but if there are better tubes out there (and the consensus seems to be that there are), why doesn't AI sell them or at least recommend them - especially if they'll improve the sound of their gear? Don't they want their preamp to outperform the competition?. The better tubes on the market are not that much more expensive than the tubes that AI sells.

You'll almost never get the "best" tube with a new piece of gear. In many cases the best sounding tube for a particular piece of gear is a tube that has not been manufactured for 50 to 70 years. In many cases it is a major search (months to a year) to find enough tubes in excellent condition to fill just one or two amps or preamps; and the tubes could sell for anywhere from $100 to $500 each because they are rare and not coming back.

Each unit someone makes and sells needs to sound the same, or who would trust to buy it. So a manufaturer needs to find a large, inexpensive, reliable and readily available supply of tubes in order to meet demand for its products.

If some hobbiest wants to take the time to search the world for a hand-full of tubes to change the sound of the gear, then more power to them.

Audio makers don't recommend other tubes for legal reasons. If you play around with your gear and the tubes and screw things up, or blow up the unit, burn down your house, they could be held legally responsible for recommending you try it. That is why every owners manual says that there are no user serviceable parts inside; not to open the top; and return it to an authorized technician for repair.