«Finally, given that I believe that the Torah is from God and that the Jews are the Chosen People, and because I have values similar to Orthodox Jews, I am often asked why I am not Orthodox. My standing-on-one-leg response consists of three Hebrew words: Yom Tov Sheni. That's not my only reason, but it's shorthand for rabbinic law not changing.»
Can Halachah ever be wrong? | Dennis Prager | Jewish Journal
Sometimes the Creative Minds [Oker Harim] forget that by chipping away at the system, that the system may lose its structural integrity.
A Modern Orthodox person sincerely may QUESTION Y"T Sheini
A Non-Orthodox person simply discards it
See Beis Halevi on "Mah Ha'Avodah Hazot Lechem"