Most people are probably holding QBs, not streaming.

However, streaming QBs can definitely be a viable fantasy strategy if:

• your league is small and the QB you drafted needs some filler weeks.

• your league-mates draft their QBs too early (so you will miss the top 10ish options while you strategically bulk up in flex positions),

• your bench size is big enough to let you keep another QB e.g. for next week.

Here is a previous analysis I made of QB streaming to support the above. 

And Disclaimer to the support for streaming: 2021 was an exceptionally poor year for QB streaming.