One of my recent questions (about the use of "either") was understandably marked as a duplicate. The question that it duplicates can be found here. While it is correct to mark my question as a duplicate, I'm afraid that the answer to the original question is probably incorrect.
My reasoning is simple. The Merriam-Webster dictionary contradicts the accepted answer in the original question. Merriam-Webster has more authority than EL&U. Not only that, but the EL&U answer makes use of nothing more than Wiktionary and Wikipedia to back up its assertions, and even the Wikipedia page is misleading, as it has no information on the relevant topic.
Below is the Merriam-Webster entry which contradicts the accepted answer that "either" can only be used informally to correlate more than two alternatives. You will see nothing about "formal" or "informal" in this entry. There is no evidence for making the claim that the accepted answer made.
—used as a function word before two or more coordinate words, phrases, or clauses joined usually by or to indicate that what immediately follows is the first of two or more alternatives [can be used either as a guest room or as an office]
The question about "either", expressed in both threads, is an interesting question that deserves an accurate and verifiable answer. Currently, there is no such answer. What should we do about this? We can't un-accept the answer in the original question, can we? It's my understanding that only the OP can do this. In which case, could my question be unmarked as a duplicate?