As someone on the outskirts of Data Science, probably something along the lines of “Just what the fuck does my customer actually need?”

You can’t throw buzzwords and a poorly labeled spreadsheet at me and expect me to go deep diving into a trashheap of data to magically pull a reasonable answer. “Average” has no meaning if you don’t give me anything to average over. I can’t tell you what nobody has ever recorded anywhere, because we don’t have any telepathic interfaces (and probably would get in trouble with the worker’s council if we tried to get one).

I’m sure there are many interesting questions to be debated in this field, but on the practical side, humans remain the greatest mystery.