I mean if you don’t have a kettle, it’s a fine way of accomplishing the task.

And if you don’t have a microwave?

a) what are you doing with your life? You’re missing out!

b) the stove top is the next option.

If you don’t have a stove top?

a) ok, now you’re most likely living rough. Sorry bro.

b) light a campfire. If you also don’t have a pot, go get one, or use some other heatproof container.