There are many, many, many "legitimate" "real-world" situations where you need data structures ouside of the two or three Go gives you by default. Queues? Dequeues? Trees, for the love of $DEITY? Tries? Sets?

Effective use of Golang is really teaching yourself to think that anything beyond the language is a useless distraction or some kind of academic pretension. I won't go so far as to call it S________ S_______, but this is textbook Blub.

I needed a ListMultimap a couple of weeks ago. Fortunately it had already been implemented for me because my language doesn't prevent that.

The last time I wrote one was a few weeks ago. I've written dozens of them during my career.