If you mean by "liberal doctrine" they strayed most from scripture, they found themselves without reason to believe. But were they really "liberal"? They had drawn a hard line not believing in the resurrection. No longer liberal, just on the other side of the truth.
That's how I see it, as well. Jesus attacked not only the belief but the office of the Pharisee's, Sadducee's and scribes. And it was the power that they had, that made them envious of Jesus message. Destroying the physical veil in the Temple, opened man to deal directly with Spirit without physical (fleshly) mediators. A practice that was returned to by catholic orthodoxy.
It drove Paul to say that he was the least of the (office) of apostles placing himself below the lead of the Spirit, while others created a path to rely on men to understand that path. An elder teaches others the discovery of the Spiritual path on their own, so they find it and become elated through their efforts. The Priests say to follow them, because they have found it for you.
Where you place your faith, dictates what you will believe. What you believe is what dictates your path (in life). And the easiest path isn't always the best one.