I would actually turn this question around: why would you want to implement your own aggregation functionality? It's super convenient to be able to just make a

I would actually turn this question around: why would you want to implement your own aggregation functionality? It's super convenient to be able to just make a histogram. And I'm sure my hexbin aggregation function would have errors in it the first time I wrote it. But these are all opt-in - if I need to make a histogram of 10 trillion datapoints and performance is critical, sure, I'll do the aggregation myself and just call the barplot function instead of the histogram function. What did bundling a histogram function take away?