As a child I had to attend a grammar school. Grammar wasn't just taught as a single subject. We had to incorporate it into every lesson of every day. We were warned of dire consequences if we violated grammar rules and I was terrified of accidentally using a double negative. Some of my schoolmates became grammar evangelists and went out into the world preaching the word and judging others for their transgressions. I became disenchanted with the concept of grammar because I could find no evidence that it existed other than in the minds of those who believed in it. However, the brainwashing I endured in childhood meant that I could never entirely leave it behind. To this day, I fear for the eternal soul of anyone I hear saying "it don't matter".
Jane S 