Is there an etiquette to #LinkedIn?

Yes there is, but it isn't always very clear.  The old saying goes: "Don't talk about religion and politics."  I try not to talk about religion, but I sometimes talk about politics.  So do my friends on LinkIn and in other social media outlets.  And we don't often agree.  That's fine with me.  I respect people having different opinions, but what I cannot abide is when people rebuke me for stating an opinion.  "LinkedIn isn't a a place for that" kind of statements offend me.