[sigwinch28]

They leave oxygen tanks littered up there.

They leave human bodies up there, too, but those are usually moved out of view.

[lm28469]

That's what I was going to comment, if they don't even bother bringing back the deads you can be sure they leave everything they can to save weight

[gumby]

I admit I haven’t climbed Everest but an important principle of the backcountry (or elsewhere in nature) is “Leave no Trace”.

But Everest sounds like an urban environment.