Backblaze only covers the drives they have in production, which is a fairly small variation. Any smaller drives you see in their stats will be older (with more data), which means you might not see any data if you're buying a more recent smaller drive, and they may not have data on the highest end as they want to hit a good price to size/performance value for what they buy.

It's more "here's a review of what we have" and less a "here's a survey of what exists to buy", although you might be able to make some educated guesses about the latter from the former (but I would consider those low accuracy).