I think I've read enough of Jingl's comments about nitpicking grammar points (my word not hers) to think she has had enough of the constant rehashing of the same old stuff - and I don't blame her. I took her comments to be tongue in cheek - that's all!
Although I've contributed to Pedants' Corner topics I do sympathise with jingl as these particular points have been fully discussed/ explained and really do not need to be recycled yet again. Some of us find the niceties of grammar interesting - others don't. (Suggest those of us who don't, simply avoid Pedants' Corner while those who do might like to read those other threads before re-starting the same discussions.)
A knowledge of correct grammar and punctuation allows you to tell the difference between the following two phrases: *'Your rubbish'* *'You're rubbish'* ( I have to admit it is better when you use a four letter word beginning with s, but I thought it might not be allowed!)