Perhaps... but there's no real reason to get rid of the tea stains.
As long as the inside of the pot isn't crusted black with old tea residue, you're right. But you know how some people are about wanting their 100 year old teapot to look like it's brand new, inside and out...
As to the not-so-stainless steel, I don't think salt water would be a good idea to apply to something already prone to corrosion. For that, I'd try steel wool to polish it.