English dictionaries are descriptive, not prescriptive. Webster doesn't make regulations about how one shall use the language. They simply describe how people are already using and changing the language. A word need not even be English to make it into an English dictionary if it's popular enough. Of course you're still allowed to despise the way some people use some language. Retard and its tenses is one I think most people can get behind not using with regards to people or as kind of casual curse. Perhaps less popularly, I hate the words irregardless and orientated as being needlessly redundant. Regardless and oriented work just fine in any case. But they are all still words and they belong in the dictionary along with descriptions of the ways those vexing people use or abuse them.