Apparently they are if you are trying to grow onion bulbs. I didn’t know that and just tried to search the interwebs to find out how long after they flower I have to wait for harvest. I also learned that you are supposed to plant the smaller of the sets to produce onion bulbs as larger ones will bolt. I assumed the larger ones were better (obviously?).
day length, as I recall, is huge with onions. It's been a long time since I grew them, but I think that once the day length is long, you will get flowers – planting dates are critical, I believe.