You're right in that it won't make a dent. You're wrong in that it's an "avenue" for better helicopters.

That's a VS-300 from 1939. It's pretty immediately recognizable as a helicopter, with all the helicoptery stuff we know and love. It took Sikorsky 16 years to develop the VS-300 from this:

Which is pretty clearly an airplane with "what if we try and put an unpowered rotary wing on top?" added to see what would happen. And that's the thing - hang a big rotor in the slipstream and it will spin automatically and it will create lift. The Nazis actually towed unpowered autogyros with spotters in them behind u-boats like kites to look around for shipping to harass and destroyers to avoid - you can literally tow a helicopter with a boat and the fucker will fly. Comes from the big goddamn blade up above. People think it's a propeller. It ain't. It's a wing. Airfoil cross-section, variable pitch, whole nine yards.

This, by comparison, is a rock trying to fly:

The thing about multirotors is there is zero aerodynamic advantage to them. Those spinny things create only the lift generated by the motive force you twist them with. Blow sideways on a propeller and nothing happens - the pitch is way out of spec for aerodynamic lift and if it weren't, they'd need to be so huge that... well, your multicopter starts to look like a helicopter.

And while you can certainly account for a rotor or two stopping on you, you aren't gonna fly great. And you better be able to land in a hurry. If you've ever messed with a quadcopter that loses a motor, you've experienced the things veering for a wall as if it were a black hole. What makes multicopters work is orchestration of the rotors and when that gets a little bent the whole affair comes crashing down.

They'll argue that it's a mechanically simple device with few moving parts. I'd argue that you've got 18 rotors and if you lose one, the other 17 aren't really going to compensate much. And yeah - you lose one rotor on a helicopter and you're sunk.

Except you're not. You need to know how to do it in order to get your license.

The rise of multicopters in the toy sphere has nothing to do with their efficiency and everything to do with the fact that now any fuckwit can fly something. It's a triumph of technology for the toy industry but nobody else cares, really. Here's a "multicopter" as used by NATO for spying on shit, starting in 1977:

It didn't exactly light up the universe because it's (A) loud as fuck (B) inefficient as all hell (C) has no real dwell time.

And that's with a 150HP Williams turbofan.

The multicopter thing is awesome for toys and purt near useless for everything else. If you want something to fly, give it wings. Full stop.