Kettles are not just for brewing tea. Whenever I need to boil large (quart or above) amounts of water (e.g. for pasta) I boil maybe 80 % in the electric kettle and the rest in the pot. Goes much faster.
At least in the US, I think that's only true for electrical resistance cooktops/hobs. For both natural-gas and inductive cooktops and 110V kettles, I find that the water boils much faster in the pot.
A combination is still faster than either in isolation!
Yes, but you would want the 80% in the thing that heats up faster, no?
I also used to use them to make noodles in college.