The challenge for political party is to prove that their political is feasible on the size of a whole country to the population. If an opposition party present a policy
The participation of the party politic will be to create one (of several) government of a community in order to test in a small scale a policy that they would like to apply on the large scale. For, an opposition party, the advantage is obvious. The coexistencialism will give them the possibility to test the future policy on the more scale and so they could more easily present their policy to the national election. For an already governing national party, the coexistencialism make it possible to do a policy that they can't do directly to the whole country but that they would like to do in future. The reason for a governing party to test a policy that they can't directly put in practice at a national level.
Author: Hector Archytas