No Modern Orthodox Rabbi ever advocated those things either. Are there people who do it? Unfortunately, yes. That doesn’t mean it’s the “official party line” of Modern Orthodoxy. Chances are, if Modern Orthodoxy didn’t exist, those people wouldn’t be keeping kosher or Shabbos at all either.
Can I add that according to the Conservative “party line”, you should be shomer shabbos and kashrus, however most who identify as “conservative” are not.