The assignment of a verb into an irregular or regular class is perfectly arbitrary. Merriam-Webster accepts either form, but Merriam-Webster is a dictionary of the American language. Last time I was in a bookstore in Kitchner-Waterloo-Eh, they were selling dictionaries of the Canadian language-eh. In Canada you measure things in metres, and play ball in the Rogers Centre, and a person injured in an accident in Ontario goes “to hospital”, not “to the hospital”, like they do in New York.
We still go “to the hospital” as far as I know lol, and I’m in Ontario. Metric - hate it. Never use it. I wish we had never gone there.