But how is that different from the personal discernment that led to "break- away" denominations? 

If truth of God is left to personal discernment alone what happens when two people reach two different conclusions, isn't objective revealed truth become meaningless?

How do you discern wrong from right if there is no standard on which to judge from?

We can find this same kind of personal discernment when people chose not to help the poor and not see it as a sin.  St. Basil the great even regarding owing an extra pair of clothes as theft against those who had no clothes. How many who follow personal discernment recognize this as a sin? 

To me it seems to lead to a path of most comfort rather than the narrow path, the church even in the bible spent time admonishing the faithful for following paths in contradiction to the teachings of the apostles. Galatians, Nicolatians, Ebonites and so forth. Were the apostles wrong from the get go?
Why not informed discernment based on the teachings?