I also wasn't sure what they meant by a "rowdy orchestral crowd".

I don't see a problem with audibly expressing one's appreciation for the composer, conductor and performers during intermissions or at the close of a piece, but IMHO it would be downright disrespectful to carry on during the performance itself.

Quoth Franz Liszt to Nicholas I, emperor of Russia, who apparently had the temerity to talk during a performance, "Music herself should be silent when Nicholas speaks".