Anything can be a message queue if you use it wrongly enough
I once used a MySQL database as a replacement for a message queue. This was the easiest solution to implement since all the servers were already connected to the database anyways. A server would write a new row to the table and all the servers would remember the last row they had already seen. Occasionally the table is cleared. I'm sure there are some race conditions in the system but its only purpose is to send Discord notifications when someone breaks a highscore in a video game, so its not really critical. It's still working that way today.