I actually think marinewank, to a certain extent, is completely reasonable. They're supposed to be near the best of the best of what humanity can create, fighting for centuries, with a creation process that has an ultra low survival rate and requires a fuckzillion man hours of effort and mountains of resources, they're so rare relative to the size of the setting some places regard them as myths, a single company is supposed to be enough to pacify a whole fucking planet, etc.
Going through the insane amount of effort it takes to create, arm, and deploy a space marine just for them to regularly get bodied by a random nob or a pack of cultists with looted bolters is too retarded and unbelievable even for warhammer.
That being said I still think they get way too much attention over the other factions, which is something I'm sure we can all agree on.