What's the deal with user-select: none on body?

I have had some issues with my ionic app in a couple of situations (in both safari and the ios app, I can’t kick off certain contenteditable interactions, and in no browser can my users select text for copypasta purposes).

It turns out all these problems stem from setting user-select: none; on body, which is SUPER annoying. Did I miss something where this is necessary to make gestures work correctly? If I turn off that bit of css, my gestures all seem to still work.

If it turns out this is critical to performance / behavior for something I haven’t yet noticed in my preliminary testing, I’ll just go and make sure I have unset that in the appropriate elements in my DOM tree (forum posts and so on) instead of just disabling that bit of CSS from the emitted ionic code.

Does anyone have insight into why it’s there and what it’s for?