Past a certain level, I do think magic item dependancy is legitimate.
EG: A powerful demon. It flys, it can throw fire, it can only be harmed by magic or blessed weapons.
This is perfectly valid monster design, and matches fantastic tropes and player expectations.
But if your fighter doesn't have either a magic bow, or a magic weapon and some way to fly you aren't going to beat it, even if its a CR5 demon and you're 20th level.
And that's fine too. Plenty of myths call for specifc magic weapons to beat the baddie. Heck even the Hindu GODS had to switch up weapons some times.
So while I agree magic item charts with exponentially escalating costs that lead to daggers worth more than the entire kingdom are just rediculous, at some point it's just fine to either expect the PCs to have aquired some key pieces of kit, or to have the GM need to be aware of the PCs lack of expected resources so he knows better than to put the flying, blasty, immune demon into his game.
Note that it would be perfectly cool to put that demon in without a way to deal with it in the first enocounter. Maybe the PCs need to run away, do research and try dipping arrows in holy water to work around the blessed blade limit.
I endorse this message and wanted to XP it but must spread around etc....