This is demoralizing...trying to use INARA to find these mats is like chasing ghosts. The life span of items listed in IRANA is about 5-7 minutes
I suspect the problem there is that Inara only gets the journal data listing bartender stock when someone visits and browses the stock. Since, as you say, demand significantly outstrips supply, it will frequently be the case that the data is immediately obsolete, because that player immediately bought the stock on offer. Unfortunately the game does not send a second journal event after the purchase, which would update the stock levels to the values that the
next visitor would see. The same thing happens with commodity markets - e.g. during a busy community goal, it's always good to be suspicious of a recently updated station listing less than one full Cutter-load of goods.
Is it for the sole purpose of keeping asses in chairs or do they hope so many people have a form of Engineering OCD?
A bit of both, I think? Since a lot of the Odyssey gameplay revolves around the upgrades, I do think Frontier calibrated it to avoid the average player running out of gameplay too soon. Certainly the number of people I hear talking about having G5 fully modded numerous suits and weapons makes me a little envious of the amount of play time they must have. But then again, I'm getting by just fine with a mix of G3-G4 gear, mostly bought from the shops at G3 with a grade's worth of additional improvements applied. It's an impressive feat of completionism to max out those upgrades, but in no way mandatory.