So when did they actually stop manastone usage in the planes?

[Erati]

you could use them in classic PoF

confirmed

( one reason I remember is bc it was the most likely place I could always have regen up due to plentiful druids around and thusly as a wizard use my Manastone more than normal )

[matrod]

I remember clearly using them also in PoH. in classic also.