political parties favour whatever voting system they think favours them.

i think that the biggest winner from the proposal that the liberals are pushing is the ndp, and that the liberals are best off with the status quo.

https://www.thestar.com/opinion/commentary/2016/12/05/lessons-from-justin-trudeaus-electoral-reform-fiasco-walkom.html

if you give people the ability to vote ndp without having to worry about the conservatives winning, don't be surprised when they take it more frequently.

but that relies on the assumption that the ndp eventually saves itself from the mulcairs of the world and doesn't collapse into toryism.