Belgium has four official language communities due to tensions between the Dutch-speaking Flemish population and French-speaking population. To reduce conflicts, Belgium implemented constitutional amendments between 1970-1993 to give equal representation and power-sharing to both language communities.
In Sri Lanka, the Sinhala language was declared the official language in 1956 and job preferences were given to Sinhala speakers, disregarding the Tamil minority who make up 18% of the population. This led to agitation and demands for a separate Tamil state, resulting in a civil war.
Power-sharing is desirable for both prudential and moral reasons. Prudentially, it reduces conflicts and brings political stability. Morally, it strengthens democracy