The destruction of the Temple did not end Jewish customs, for sure. One of the points raised in the article though, is that without the Temple, there is no substance to these customs, without the practical means to carry out many of the commandments of the Mosaic covenant. How can one cleanse oneself, and receive atonement, if one is ALWAYS in violation of the covenant because of this situation?
Many Jews nowadays believe that this mortal life is all that is there for them, despite the promises in the Torah of the resurrection. I believe this is just a symptom of trying to reconcile their belief that the Messiah did not come yet, with the situation they are in: not able to expect all the promises of the Covenant, since they cannot fulfill their duties under it.
This is a kind of spiritual pessimism, and the only cure short of reestablishing the Temple (which would have to be commanded by the Lord, since He removed it), is the Messiah.
Actually they still perform them but at the Mount of Olives. And it’s symbolic.