There have been instances where a party that secured 3% of the vote wields more influence than one that won 30% of the vote. That's when the democratic system no longer functions as it should.
Whether a party has the support to give it the right to govern entirely according to its own thinking without having to find support from another party depends on the total electoral support it can garner. Don't think a political system that gives it the right to do so when its support is not totally comprehensive is a walk in the park.
If close to 50% is against its policies and if the implementation of these does not bring the desirable results, the disapproving voices will grow in number and it will be thrown out at the next election. The next government also with just a little over 50% support will face the same problem and the cycle repeats itself.
If the population is split more or less in the middle for or against a certain way of doing things, surely the solution is not to force upon the people one extreme outcome or the other but rather to work out a solution that is a compromise satisfying both POV to some degree.
Why wait until the next election to see how the alternative will work out when you can have (provided the system is right) the opposite POV taken into consideration right now instead.
I don't see such a big problem for two parties to work out a compromised solution as often one party could be more supportive of one segment of the electorate while the other could be for another. But both segments of the population constitute the same electorate which both parties are keen to gain its support, so why not do something good for them?
Especially in an environment where there is majority support for a very long time, what is the problem to take into consideration the views of the opposition members in Parliament or if there is no majority party, in a coalition government.
In an environment where support for the parties are so balanced that the seat of government changes hand regularly, there could be attempts to sabotage the ruling party's plan. Whether such a situation actually arises or not is a result of the political environment and not a fault of the political system.
The way out of a situation like this is to have a governing platform based on a set of policies that will even handedly take care of as many people as possible so that you can get a strong, clearcut majority. This way you will get a lot of support for your policies.
As it is, a substantial number of people are left very unhappy.
