Much as I dislike literally==figuratively I'm not sure what descriptive vs. prescriptive has to do with standard reference. I'm somewhere between the poles. On the one hand see figuratively comment. On the other hand, languages are living things. And, to my example, if you tell me you have four fingers on one hand, I'll ask you how the accident happened.

I also think you'll find a lot more organizations that use MW as their reference standard than other US dictionaries.

Descriptive: Describes how people use the language.

Prescriptive: Describes how language should be used.

Descriptive dictionaries are highly favoured by those who like to effect change (I'm deliberately avoiding the word Liberal because I'm not in the US and I understand that word to be politically charged for many HN readers). Prescriptive dictionaries are more favoured by those who keep traditional values. Descriptive dictionaries can be used to say "I'm using the word correctly" and prescriptive dictionaries can be used to say "you're using the word incorrectly".

But organizations mostly want to talk to people in the language that they use. They have zero interest in being the language police. They may decide that their writers shouldn't use literally to mean figuratively. But, at least where I work, we're mostly interested in using the language that best connects to readers.