Boiled eggs. Keeping a special pan.

Just curious. My DM always insisted on having a dedicated pan for boiling eggs and would never use it for anything else. The water used for boiling would be thrown away. She would never boil vegetables in it for example. She was born in 1915. Was this typical? Was it because of the sulphur from the eggs discolouring the pan? Or was it to do with the toxic metal in saucepans in those days, leeching out into the water?

I haven't heard this advice since but although I wouldn't cook anything with boiling eggs in the same water, I would use the pan for other things. My pots and pans are stainless steel.