I'm not talking about streaming live data, I'm talking about streaming query results if you re-read my comment.
If you're reading many MB's or GB's of data from a database, it's a lot more performant to stream it from the database directly into your local data structure, rather than rely on default processing of query results as a single chunk which will be a lot worse for memory and speed.
Streaming aggregation relies on knowing the problem beforehand, so it's pointless in the context of the day-to-day work of analysts where most of the project is spent figuring out the right questions to ask.
If I need to stream data because the size of data is a constraint, I'm either working on the 0.1% of projects that require it or on an analytical product rather than an analytical project.
If you're reading many MB's or GB's of data from a database, it's a lot more performant to stream it from the database directly into your local data structure, rather than rely on default processing of query results as a single chunk which will be a lot worse for memory and speed.