Why does Windows 8.x's autocorrect suck?

Simple question. WP's has always been great, and even better in 8.1 since you can train it to recognize swear words. So why is it on my surface if I'm writing something like a proper name that's not on the dictionary, I have to delete and retype it 3 times before it stops replacing it (and only then be able to add it to the dictionary)? Where is the option to revert a correction just by tapping? Why is it different from WP at all?