Right, but if the point isn't for the drive to be actively used, and instead just hold data for archiving, then there's little reason to spend more money to get an SDD for that purpose when an HDD will hold that data just as well and for much cheaper.
The benefits of SSD over HDD are almost entirely in performance, so if SSD can develop further to provide a tangible benefit over HDD for long term storage, and do it for cheaper, then we can fully move away from it. But I don't think we're quite there yet.