Hawk Diesel
Adventurer
Maybe an atom shaking frequency? That seems to align well enough with all of the given examples, and Shield can simply be said to counter the particular frequency used in MM.
I mean, I suppose you can say that. But from my perspective, there is no difference between atoms or frequencies that would differentiate between atoms in living things and those in non-living things. Which brings us back to the original problem regarding how Eldritch Blast can target living creatures but not objects. And even the living/non-living thing is questionable because you can target animated undead or constructs.
I think there are some things that just exist as mechanics, and attempting to rationalize them is just going to open a can of worms and give a lot of people headaches.
Personally, if I ran a game, I would have no problem with a warlock character targeting an object with Eldritch Blast. I honestly don't see a reason it couldn't, and it is certainly not game breaking to allow it.
But with regard to the OP, I really do like the explanation. It's great out of the box thinking. It's just also that you can't look too hard at it. Just something you kinda try to accept and move on.