... I guess it was put in to annoy, in which it has been successful

Basically its was an argument that ecological concerns have turned the garden into a place of guilt. She says "we are exhorted to plant only natives (which strictly interpreted, would give us a choice of maybe 50 plants, mostly prickly)"

Firstly the exhortation has been to plant more native plants, rather than only native plants, and now the advice is merely to avoid too many double flowers. Secondly, "choice of 50 plants mostly prickly" gives a misleading view of the British flora of over 3000 species.

From the RHS report into Urban Gardens: gardens "contribute from 22–27 percent of the total urban area in many cities, and can represent nearly half of urban green space. Domestic gardens contain approximately
25 percent of the total non-forest and woodland trees and can contribute as much as 86 percent of the total urban tree stock."

So is it really unreasonable to ask us to be aware of this, and to have a mind on wildlife while we garden?