To be fair to them, they’re dealing with a lot “strategic” voters. Two elections ago their votes really weren’t all that far behind the other two. For their 3.5mil votes they got ~25 seats and for their 5.5mil votes the Liberals got ~155; since people only see seats they just assume that NDP aren’t popular. This last time people got really “strategic” because the Conservatives are fucking awful and going even harder at it than ever. Every time we have a cycle that, things get just a little bit worse and now we have to claw ourselves out of it from so much further down the hole.
Even in first past the post anyone can win if you vote for them. The problem with the system is the scare tactics centrists can use to get votes from progressives. We need ranked choice really badly.