Party Balloons are a real thing. I have passed several on approach into LAX. Regardless if they are a thing to be concerned about, I reported them to approach. I think hitting one would be a non event but I would rather no find out.
Regulate a balloon that slipped out of the hand of an inattentive 4 year old is a bridge too far.
A Balloon club launching a hobby balloon into the jet route structure would likely have only slightly higher chance of disrupting things but still the potential is there and should be mitigated.
Sparky