After a flurry of activity in the last decade, I haven't heard anyone mention adult coloring books even once in the past two or three years. As long as we're all baselessly speculating, I will baselessly speculate that they were just an ordinary fad. My own anecdote is that disillusionment with internet content and electronic consumption in general has caused me to buy and read more books recently than at any point in my life.

They are prominently in bookstores. They did not disappeared and people did not stopped buying them.

Just the hand wringing over them stopped.

Come on...

I'm blaming self improvement books.