The rules of grammar, punctuation and spelling are not carved in stone, contrary to the language Nazis who would like everyone to adhere to the rules they grew up with from elementary school.
Rules change as popular usage changes. If everybody quit capitalizing the first word of a sentence, pretty soon that would be the new rule.
The rules are apparently changing again with regard to whether to put punctuation inside or outside of quotation marks.
For at least two centuries, it has been standard practice in the United States to place commas and periods inside of quotation marks.
(snip)
But in copy-editor-free zones—the Web and emails, student papers, business memos—with increasing frequency, commas and periods find themselves on the outside of quotation marks, looking in. A punctuation paradigm is shifting.
Personally, I like putting the comma and period inside quotation marks. Look cleaner than way.
But there are times when it looks stupid -- such as with a question mark.
Here's an example:
What did you think when John said, "I don't like that brand?"
Another rule that is changing is whether to use a comma after the final element in a list, as in this:
John bought celery, lettuce, radishes and peppers at the store.
Should there be a comma after radishes? When I was in school it was drilled into me that there is no comma before the conjunction.
But, hey. It's just a rule. And rules change.