Right now items only have value if they're able to be sold on the flea market or if they're an FIR quest requirement. If you can reliably rush high value loot (marked rooms, resort), win fights and make tons of money, there's no reason to ever stop to pick up bolts, hoses, etc. if you can afford to buy them in bulk after selling a single LEDX for 2 million. The meta for quick progression and money making is really to just rush the same cash cows over and over and sell them for money to upgrade your hideout, or quest items that don't require FIR tags. If you're learning the game, you start to learn which items have flea market value, ignoring lower value items as you progress, and farming FIR quest items when you find out you need them. If this isn't your first wipe — you already know most FIR items to grab.
Imagine they remove the flea market. The meta shifts from rushing the cash cows, because for example, a LEDX is only worth what it can get you from traders and quests — still valuable, but diminishing returns after finding/farming the first four. If you can't buy all the upgrade requirements via flea market, every player will be encouraged to loot different sources for upgrades and quests. It would promote exploration, diversify player traffic, and it would mean that virtually every item that can be found would have unique value to the player, instead of being an instant toss because it's worth under 20k rubles.
I really haven't fully fleshed out how they would implement this, but I know there was a time when the flea market didn't exist and the game survived then. They'd probably have to make traders more robust and adjust vendor prices. But with that in mind I think it's totally viable — would love to hear what people think.