Do keiyōdōshi exist?

Keiyōdōshi (形容動詞 – ‘adjectival verbs’) are a class of declinable words such 静か and 堂々 that take the auxiliary verbs だ, なり, and たり. The classification is widely accepted in Japan and is recognised by highly reputable dictionaries such as Daijirin and the current Kōjien. It was not, however, accepted by Shinmura Izuru (新村出), the …