Unlimited Bots in Rivals

Who are these players who have accounts like ZASDGadfa235?  They must be bots, there's hundreds of them, they leave before entering a match  or just let the timer run out.  I block them and they keep appearing, very annoying.  The vast majority of them have user names that fallow this patter XXXXXxxxx1234  (cap letters dash lower case and then some numbers) .  Why is this nuisance allowed?  Makes user experience annoying.