Having said that, I agree that for a starting user or for someone who doesn't know about coding may think function maps are too confusing and even overkill, demanding a lot more typing than using a bunch of if-elses. And for a small project it is true indeed.
But, for a huge game with lots of levels, upgrades, skills, and so on, mapping functions to execute similar actions with different parameters will be a huge boost in your coding process and also with readability and maintenance (just like the JSON dialogue system Laura_D has pointed).
So, what I really wanted to say is that function maps (along with the scripting feature) is a powerful tool that allows us to make bigger projects, and elevates Construct 3 level against other competitor game engines.