everything gets abused offshore! It's quite common for stuff to be stacked on pallets and left under a tarpaulin for days or weeks, or containerised and shipped for two or three weeks at a time.
The main aim is that it survives at all, and peli-cases certainly do that. Immersion isn't really a consideration.
It's also the case that items stacked on pallets are usually lashed down, either with ropes or ratchet straps, which could stress boxes assymetrically. Boxes stacked in containers could have a considerable weight on them; not tinnes, but enough to distort a box slightly over two or three weeks.
Offshore procedures don't involve immersion, much equipment is shipped in aluminium hinge-top cases which are robust but certainly not waterproof.
The other thing I particularly like about the peli-case type is the security of the moulded handles.
''the stopes soared beyond the range of our caplamps' - David Bick...... How times change .... oh, I don't know, I've still got a lamp like that.