We can start with what the author just said.

1) It saves you from crashes and other crap

2) If you are collaborating with anyone ie. using git you can forget about them anyway unless you wanna face merge hell.

3) Interface builder is difficult to use, is definitely lacking advanced features so you'll end up putting some UI logic in the code anyway => more complexity, more error/mistake prone etc.

I have to say I'm a bit surprised to see this kind of reaction here on HN. I never thought anyone real developer would use them for anything else than just quick prototyping maybe.