For example, we have transactional data. You would love to have aggregations like how many purchases was done in last 30 days (you want this information for each row in the data) or sums of purchases in last year (not in exact year, but floating year based on some datetime variable). This is not now simply possible. This is useful for preparing modelling in areas like churn or predictive maintenance. It can be inspired by SQL windows functions.
It true, the "floating aggregation" would help us a lot in one of our last POC regarding Predictive maintenance.
DPaula