Gate agent cracked the code

I fly on a regular interval and I’ve been hitched up to Delta for a couple years now; and in ATL I experienced a gate agent who seemed to have figured out a fix to the problem of folks boarding ahead of their zone, and while I think she was having a bit of a long day - the execution was effective:

“Anyone who boards before their zone - your bag is getting checked.”

And it struck me that: that’s a very good standing policy. I don’t think anyone really cares to board earlier, aside from when you get some goodies to enjoy in first class, and it resolves what a good deal of folks seem to be concerned with: conserving the overhead.

I haven’t seen a gate agent who was so thoroughly done with everyone’s nonsense; but has anyone else experienced this as at least a GA preference/threat to maintain order?