Shikron is correct. Chazal say that although Hashem favored a single stone altar in the time of the Avos, once the idol-worshippers started using it, it is not to be used.
The same has been said about the learning of Tanach and Dikduk in Yeshivos, once the Maskilim started being all into it. (Of course one should learn Tanach on his own)