Eh, a lot of those problems have solutions, and some are more theoretical.
Yes, if you design your graph to allow something like `tags -> relatedTags -> relatedTags` ad infinitum you can let your clients build a performance problem. So why not have just a top-level `getRelatedTags(tagName)` query? Or a `getRelatedArticles(articleId)` query? Just because you can have things nested doesn't mean you need to have all the things nested.
The bulk of our REST API is backed by some Rails gem, which allows for a `fields` param. Those `fields` can be deep. As in you could write `getComments?id=1234fields=user.orders`, but do you know what we do? Don't expose `orders` as a field on `User`.
