There are something to those tests, absolutely. But you need to know how to interpret them. What were the antibodies you tested positive for? Supposedly, they’re precursors of actual disease which will manifest after sufficient tissue damage. So you can detect autoimmune antibody attack during the asymptomatic phase and take proper action.
I’d personally take them if I can afford the cost and know how my body is reacting and whether there are any antibodies that have been activated. Much easier to react then than when symptoms appear, by which time it might be too late for many autoimmune diseases.