Re: Just what is the etymology of such an expression?
north Americas 'dumbed down'
That's a tad harsh - the US spellings were deliberately simplified to make it easier for the many immigrants from non English-speaking countries to learn. Which still gave plenty of space for eloquence and elegant language.
No - for the current state of US grammar and spelling you have to look no further than the abysmal teaching of English in schools. And we in the UK are follwing suit.
(Lets be clear here - I'm not blaming the teachers - I'm blaming the system and the methods that don't allow the teachers to *actually* teach proper English)