Because 99% of the time English will not respond with a compile or runtime error when your input to it is slightly malformed.

Because english isn't as standardized as we would like to think. The written and spoken forms are not a one to one translation. Written english could almost be classify as a seperate language that happens to share words and similar syntax. At least the written version has a modest level of standardization. The spoken language is very fragmented.

From a linguistics standpoint, all paired written and spoken versions of languages are considered separate languages.

"at least the written version has a modest level of standardization"

O rly?

srsly, tho, there are lotz of ways English is writ, la?

thks cellphones! lol

I wasn't referring to spoken language. I meant when people try to literally "write like they speak" and end up sounding ridiculous because, as you said, written English could almost be another language.

Several, don't forget dialects.

Because there is no such thing as correct English.

OK, so what is the politically correct term for the use of, say, a double negative in English?

The preferred euphemism used to be "non-standard", which still leaves the problem of defining "standard" English.

Right, I like to think that there are milieus of English with which knowledge and conformance can be useful. Formal writing for example. But to say that the rules of formal writing should be extended to all domains is akin to saying that all food should be stir-fried. Just like there is no such thing as standard cooking, there is no such thing as standard English.

We need to keep adding levels of euphemism, until it's euphemisms all the way down. Only then will the egos of half-wits be completely safe.