I don't believe in any conspiracy theories for one simple reason - love them or hate them, all referees in top class football, throughout the major leagues of the world, have spent many years training, learning rules and adapting to new ones, going through assessments, learning their craft. Throughout the time of a Premier League level referee he would have spent hours and hours officiating, in the middle, running the line and as a fourth, games right through from amateur and junior all the way up to the top flight.
As an armchair pundit and one time poor player, I am amazed that they are as dedicated to their jobs as they are considering the crap they have to put up day in, day out.... and they don't even get to kick the ball!
They aren't perfect, of course, but who is? Maybe they have an underlying bias sometimes, maybe they aren't that good at their jobs (I am definitely not one to comment on that!), but overall I think they do a pretty good job most of the time and deserve our respect (except when they make a decision against us!).