South African politics have always been party politics, and not really whether those in parliament actually deserved to be there, or were accountable to anyone but the party they belonged to.
In simple terms, the South African system is a proportional system. That means that each party gets to allocate a proportional number of members of parliament (MPs) according to the percentage of votes it garnered in an election. If there are 162 positions for MPs, and party A got 23% of the vote and party B got 53%, then party A will get to put forward 37 of its members to be MPs and party B 86. This way, the voters will never know whether these MPs are really capable of doing the job, or whether they have a sense of accountability.