[GingisK]

I can't think of a single instance where a really tall building would need to be scaled from the outside in a combat operation. That aside, you can use a grapnel on very tall cliffs by just shooting it from a mortar or using a rocket assist. Tall buildings are best scaled using cruise missiles at the base.

Modern tactics generally don't need this sort of activity.

[buwaya]

The thing about innovation is that it opens use cases you may not have thought about, yet. Maybe.

Consider the military utility of the 1866 Winchester rifle. Weak cartridge, very poor range, no bayonet(!), a lousy fit for infantry tactics of the day. A toy for civilians, or maybe policemen. However, Turkey bought many thousands of them (with lots of kickbacks knowing the Turks).

And then at Plevna, 1877, these things, used in mass, shattered one Russian infantry assault after another.