Proportional representation meant that lots of different political parties were able to win seats in the Reichstag
Sometimes there were over 20 different political parties all arguing over a single issue
This made it difficult to make decisions and introduce laws
In fact, between 1919 and 1933, no political party ever won more than half the votes in any election
As a result, they didn't get more than half the seats
With no majority, the leading party had to do deals with smaller groups in order to get anything done
Again, this made law-making a very slow process