There are limits to breeding which cannot be exceeded by diet. There is a large amount of research from the poultry industry (about raising squabs for meat production) in which all sorts of different diets have been provided as attempts to improve production (and profit) -- despite which there is always a point where more food does not equal greater production even in "ideal" circumstances for breeding.The problem with feeding is that it encourages breeding.
In natural environments as well (most notably in Scotland and Ireland), no matter how much food is naturally available to pigeon flocks within the environment, there is a limit to the size of the flocks due to the number of viable nest sites (on sea cliffs), rather than the availability of food growing in nearby fields.
Any city where buildings and other man-made structures provide numerous nest sites for pigeons will always have pigeons in evidence regardless of the amount of food within the city because the birds are quite capable of flying to fields outside the city to forage for food -- and indeed, that is exactly how they behave in their native environments: they nest on sea cliffs where no plants grow, then they travel to fields to forage. No amount of feeding within cities changes the number of available nest sites just as no amount of fields near cliffs changes the number of nest sites on the cliffs. No matter how many acres of plants are growing around a city, Rock Doves do not nest in fields -- they nest on elevated ledges of cliffs, or the equivalent human-made structures such as buildings, overpasses, and the open-but-covered features of mass-transit systems. The presence of pigeons in cities is entirely the fault of the bad design of human constructions.
On the other hand, concentrating a lot of tasty seeds in one place tends to draw notable flocks of birds which are then very evident to other people, many of whom seem to be outraged at the mere sight of anyone caring for anything other than them. Scattering seeds thinly over much larger areas would draw less attention to the birds. While many localities may have prohibitions on scattering food, very few (possibly none as I haven't found any yet), have any prohibitions against scattering grass seed where grass would be allowed to grow, and pigeons can and do eat grass seed.