Every devotion is open to abuse. Every faithful doctrine is open to heresy. You don’t suppress the devotion or the doctine because evil can subvert it – rather like throwing out the baby with the bathwater.
And, yes, every parish in which I have ever lived (St. Louis, Chicago, Atlanta, Cleveland and now Alexandria, VA) has had May crownings. Some were “bigger deals” than others, but they all had them.
What I DON’T see any more is home May crownings. When I was a girl (and the dinosaurs roamed the earth

) one of the things that so drew me to Catholicism was my best friend’s home and family. They always had a little altar for Mary in the girls’ room and, on May 1, had a family May crowning with an aluminum foil crown. I, of course, was left out of this devotion (being Protestant and all) but always longed to participate. So, when my own girls were little, I got the chance!