Tape is also incredibly slow and difficult to scale. Also, the equipment needed to operate a cluster of tape archivers costs a lot, while they are using their own designs dor servers, with coXmmodity hardware in them.
The reading/writing speed of tapes is excellent, better than that of hard drives, so writing a backup takes less time.
For archives that are accessed only infrequently, tape is more reliable and also faster.
If you want to have access in less than a minute to any part of your backups, then yes, tape is inappropriate and you must use HDDs.
Tape is still the best backup medium for many small and large companies.
And by the way, how fast do you think a service like Backblaze is?