What do Oppositions do? They oppose. Why do they ‘oppose’ in the first place? Well, they are supposed to keep governments on their toes, help keep things in line, point out flaws etc. In a nutshell, offer constructive criticism and, in the event that parliamentary majority and executive authority is abused, mobilize the people to mitigate.
In an ideal world, that is.
What happens, typically, is that the Opposition or rather the major player(s) in the Opposition allow the intention to capture power governs word and deed. Mountains are made of molehills, sand is thrown in the wheels, typically. Such has been the bread and butter of oppositional politics. Such has evolved into being the crux of oppositional culture.