I may have some doubts with some mobile games having an "esports scene" but there are some games that have complicated mechanics, require skill, and are competitive in the slightest sense. MOBAs are already competitive by nature, so a mobile MOBA having a competitive gaming scene would make sense.
Most mobile MOBAs in Asia like Mobile Legends, Arena of Valor, and Honor of Kings have esports competitions in the countries they're mostly played in. WCG 2019 even added Honor of Kings to their list of official games, although exclusive for Chinese players only. But that could be a good start in giving mobile games the recognition they deserve.
Don't mistake casual games on mobile as "Mobile Games Esports." There are games that deserve the "esports treatment" based on their game design and games that just simply don't.