Crabapples are a great source of food for winter birds. I’ve noticed, some years, that my crabapple has a huge crop hanging on its bare branches, and it seems to go unnoticed by the birds for many weeks. Then suddenly, it’s discovered and within a day, the fruit are gone. Starlings seem to love them especially.
It takes a lot of a tree’s energy to mature a crop of crabapples. Some varieties hardly grow any new foliage or branches in years when they have a heavy crop. Conversely, if there’s little crop (for example, after a late freeze destroys the bloom), a tree can really grow like crazy.
I would never seek to eliminate crabapple crop because of its value to birds, and because the plant growth regulator that does that (Florel) is applied when the tree is in bloom, causing the flowers to drop. Seems pointless to grow a crabapple when you eliminate its two most attractive features!
Florel is great for eliminating true nuisance fruit, though. Liquidamber pods, those spiking things that you used to play with as a kid, are a good example. Few homeowners use Florel, because they have trouble getting a sprayer that can reach up into a tree. So most people ask a yard servicer to do it.