OpenAlias is a project by the Monero core team but is not specific to Monero. Should we consider it off-topic when the question is not directly related to its usage with Monero?
Adoption of OpenAlias by non Monero entities will increase exposure of OpenAlias and by extension of Monero whether the entity adopting OpenAlias has another direct Monero connection or not.
I think it is on topic. There is no better place on the SE network to ask an OpenAlias question than right here on MoneroSE where its creators are active and available to answer questions.