There is no point having a parliament or MPs if big parties are allowed to dominate

The advantage of a parliament over a single president (or mayor) is that legislation has to meet the approval of more than one person, a majority must vote in favour of it. Each politician is able to veto (reject) new law with their vote in the chamber. The presence of Fptp negates this advantage because at the constituency level, representatives are generally sent from one of the two main parties. It is the leader of the winning party which ends up in control, as Prime Minister, in a similar fashion to an absolute president. In this manner, the advantage of having a parliament is destroyed because a single parliamentarian is taken from each seat.