For example, if you want to be able to aggregate revenue by subscription plan and by country over year, month or day, then you would have 6+ different aggregations. The more dimensions and time periods you add, the more the various combinations blow out. (I think the formula is dimension permutations multiplied by the number of time periods.) Having a single definition of the metrics prevents errors from occurring in rote implementations of the metrics. A bit like generics, but for queries.

At this point, I'm curious how they manage to make the integrations with different platforms work. (Ultimately, I think that's why they acquired Transform.)