Simple farming, or horticulture, is not as such a causation of civilization, and within primitivism I see its use as being desirable. There is necessarily time of transition in coming to this, possibly for much of a remaining lifetime, while starting off with yet some dependence on civilization ahead of coming to real independence. In calculations there is no way to expect realistically that all the great collections of human populations are going to immediately change to the most sustainable way of living. Those that do, which would likely be less than what may optimistically be hoped for, but I promote that hopefulness, make less demand on the world than those remaining with civilization, their absence from civilization diminishes in relation the demand of civilization compared to the alternative of those who would make the change remaining, land being more available than otherwise, with better more sustainable and efficient use. I particularly endorse growing vegetation needed with diminished or eliminated dependence on meat from animals, which clearly makes more ecological demand. Remaining civilization will not make less demand on land per person.
Others have indeed done much good. In light of highly probable crises of which primitivists are aware, it might be said all such good things, good as they are, are not enough for dealing with everything. It can be conceived that there will be some of humanity building their society without civilization in numbers that will work, in this incorporating justice that is desirable with associated characteristics. This is what should be done in Christ.