Reply To: Kezayis only for Pesach?

I don’t understand how one can say one is not yotzei Maror with horseradish when the gemara says tamcha is good and the Shulchan Aruch codifies it and the Mishna Brurah writes that if lettuce is hard to clean than certainly one should use horseradish.Furthermore the Mishna Brurah writes that if one is sick or sensitive they can pick any one they choose.I understand that chazeres is preferred,but to say one is not yotzei?!