In reply to Trangia:
The great part of all this below the water line.
These operations are industrially organized to get as many people as possible up a mountain and away again, meaning there's a huge surge of resources up at the start of the seasons with porters and helicopters from across the country to move it all, then the entropy and randomness as it all does what it does then trickles away again. The resources and motivation to move stuff out again weeks later just doesn't match up. Whatever the value of the O bottles, it simply doesn't match the labor cost to carry it away again, and stuff left in some areas for 'removal next season' accumulates, with enough deteriorating or being frozen in to not move before the next layer arrives. In Nepal it's 2 seasons generally a year, x +30 years now.
Another sad baseline is that the environment of EBC, the Baltoro etc isn't that of wilderness, they are shanty towns on glaciers. The very locations these days are physically made of shredded tents, frozen waste, buried cans and dumps of spent gear - all bearing labels in every language you can think of. Like tossing a paper cup during mardi gras, the general landscape of already dumped junk makes it feel a drop in the ocean. O bottles are just part of the wallpaper, even despite actually being quite valuable, but recall this is an industry paying $1000 for shoes (the parallels to the high fashion industry are ubiquitous).
It is a disgrace - our ilk has turned the worlds highest and most fragile wilderness ecosystems into trash heaps. You can't touch the ground in some places it's so filthy. We've known this for decades and only accelerated. I had a decade gap between visits to some peaks I've been on and it's simply and utterly beyond words. The decade before what was a tiny and isolated cluster of tents and some barely discernable tent sites on the route had become stepping stones of yellow nylon, frozen piss and meal packets and a macramé of bleached rope to the soundtrack of the clunk of O bottles being stepped over. I won't go back, but two will fill my place.
As my partner often says, "if they can clean up after Burning Man why the hell can't they do it here?". And the answer is the industrial model used to do it. It's a blend of struggling economies locked in seasonal employment, corrupt authorities, new industries experiencing a gold rush with no regulation, product companies falling over themselves to sell shit to it, new and redirected affluence and 24/7 hype.