The Gemara in Pesachim talks about soaking Matzah in water, and had no issue with it. Rashi in Brachos (38b) also had no problems with it.
I believe the Shulchan Aruch HaRav mentions the chumrah of not eating gebrochts. It began mainly among chassidim.
R’ Moshe Feinstein held it was not a problem. The Vilna Gaon held that not eating gebrochts took away from simchas Yom Tov, and held that people should not follow the chumrah.