It's Hermès's own doing. They have created the scarcity (intentional or otherwise), and the stores needed to determine which one gets to buy the coveted items first, and there is inventory that needs to move because rent and salaries need to be paid, and so to hit two birds with one stone stores decided that those who buy more non-coveted stuff gets to the coveted bags first.
And since there are more people having more money, not less, wanting to buy the coveted bags*, there are more people who buy more unwanted inventory just to get to the coveted bags faster. One would think with that amount of money people would just go to resellers to buy bags, but the truth is a lot of people still want the store experience (new, fresh out of the box), not to mention that even with the most reputable resellers fakes still go through, so a lot are afraid to venture to resellers and just stick with buying more and more stuff they don't even want.
The "buy more other stuff, get more love" has always been used in Hermès business, even like 15 years ago. It's just now that it has become more apparent. Back in the early 2000's there was a VIP member here who even gets rare croc Birkins (as in colors not offered to everyone, sometimes she even has custom colors made for her). She was asked what she did to get to the VIP status. She said, "buy a lot of RTW and furniture! hahahaha"
And when she posed with her Birkins she doesn't even wear H clothes. She wore other designers like Versace. I remember she only wore H RTW when it had fur. So a lot of her Hermès RTW just probably sat on a pile somewhere, untouched.
*this is why the pre-spend game is not really a thing in Europe; most people don't care much about Birkins and Kellys