Grammar Issues

I'm really picky about grammar. Like really picky. I get upset when people don't know the difference between

whose/who's
there/their/they're
to/two/too
your/you're
its/it's

It also makes me cringe to hear things like, "I could care less." (If you could care less, then please do. It wouldn't bother me that you cared more or less about whatever it is you care about, because by now I've moved on.)

So when I watch sports, this gets on my nerves. It's the word "winningest."

The winningest coach.
The winningest Michael Phelps.
The winningest team.
The winningest Chinese athlete.
The winningest basketball player.

Are we Americans that lazy that we can't say, "The coach with the most wins," or "Michael Phelps is superhuman and a freak of nature?"

Well, I did some research. To my surprise, it's in the dictionary. But let me tell you, it's in there as an "informal" word. So if it's informal, why are we reading it in headlines?

For crying out loud.

-10-key princess