The animal rights people may be wacko and not neuter them, but I will tell you animal WELFARE people - at least where I am - have a spay/neuter and release program in most counties around me. They don’t want the problem getting out of hand. They don’t have the resources to deal with huge numbers of semi-wild cats.
The programs where they neuter and spay does help keep the numbers down. The problems where we are are the farmers who like having the cats aroundto take care of mice and such, and as they are feral they don’t have to feed them. The farmers don’t want them spayed or neutered because this reduces the number of cats that ‘work’ for them.
Where I volunteer as a socializer at a local no-kill animal rescue shelter/adoption center ( in CT ), cat/kitten side of it, we work with other animal organizations to do a trap/spay/neuter/release program. This helps keep the number of feral and semi-feral cats down.
My shelter also places cats that cannot be adopted in regular home enviroments because they could get “agressive” towards people or other cats or other pets to farms/barns so that the mice rodent populations can be kept in check. =^..^=