The problem with drones is how to move them. Lithium batteries would last only for some minutes if you need to support a lot of weight. And then, your expensive robot would just burn somewhere
An electric cable would put electricity and water together, create sparks that could reignite some areas, and add new dangers in form of chopping rotating blades and maybe swinging cables.
A drone in form of a flying fire extinguiser could be a better idea than a hose-drone, but still would need to fly and keep stability against powerful convection currents caused by the fire.
And of course you can forget anything with combustion engines or hydrogen fuel on it if you plan to put it in a fire.
An electric cable would put electricity and water together, create sparks that could reignite some areas, and add new dangers in form of chopping rotating blades and maybe swinging cables.
A drone in form of a flying fire extinguiser could be a better idea than a hose-drone, but still would need to fly and keep stability against powerful convection currents caused by the fire.
And of course you can forget anything with combustion engines or hydrogen fuel on it if you plan to put it in a fire.