Arabis is part of the widely prevalent Brassica family. The husbandry of this species of wild plant (Brassica oleracea) into cultivated forms such as broccoli, cauliflower and kale has occurred throughout human history, resulting in a common food source. The process of husbandry is concerned with selection and the prioritisation of economic gains. Aspects of an organism you want to keep you nurture, things you don't like you get rid of. Like a sausage dog (arabis is also part of the mustard family).
Goats are employed to browse (goats are not biologically classed as 'grazers') on the Avon Gorge where the Arabis grows, to control other plants which compromise its growth. Goats will eat anything, but mostly, they prefer the woody tips of shrubs and scrub, in particular the trailing blackberry and other Rubus-family plants, which block the light reaching the low lying rock-cress. The Arabis is regarded as a biological asset and so conservation efforts are in place, such as the amenable goats, who are good at climbing the rock face. The men send the goats to help the plants.