No it's not. The referee is just the shortest practical path to enforce a set of rules, which are the real essence of the sport. This is why people play just fine in parks without referees.

Refs are there to enforce the rules; if the same set of rules can be better enforced by other means, referees should be replaced. Subjective referee calls are a plague on the sport, and they are a prime cause for the dismal amount of corruption in it. The sooner we can get rid of them (or at least reduce their role), the better.