Rabbi of Berlin:
A. I think you misunderstand my comment about d’oraisah and d’rabonon. I am well aware of the ramifications of something being d’rabonon. I was only criticizing an attitude I perceived of not caring about things which are “only” d’rabonon.
B. That is not the way poskim paskin. They look at the most recent and most accepted opinions. An opinion which is brought by the acharonim carries far more weight than one which is not.