Before I switched to my big NAS, I had 7 extra USB drives attached to my old ones, daisy chained over two USB 3.0 hubs. The USB connection was never the limiting factor.

You would need something like 3 people simultaneously streaming a 4k movie from 3 different HDDs for that to be an issue.

HDD speed itself might be more limiting, but still would require multiple very high bitrate streams to max out the read speed of a general USB drive.

In the past!

My 20TB drives cost me $17 per TB 2 years ago. The exact same model is now at $33 per TB :(

My NAS has a limited number of bays, so buying more low-storage disks isn’t a great option.