Because we are in a state of a minority government, if there is a vote of non-confidence, then the GG has the option to either ask the next largest party to make the government or to call new elections.
The opposition dictated to her what they saw as reason to call a new election instead of asking the other parties to make a government.
They tried to outline what sort of votes would constitute non-confidence. eg that throne speech being defeated is non-confidence, the gun registry being defeated is not non-confidence.