Seems most any NAS system today should come with at least some degree of flash either for tiering or better yet for caching(even if for just reads, and/or metadata).
Their general purpose NAS data sheet makes no mention of the word flash, has no mention of how much memory is available for cache(and how that memory is used e.g. mirrored write caching), the only mention of the word cache is with their Broadcom RAID controller with 2GB of cache. Given they are using hardware raid controllers, there are raid controllers that could handle the flash caching for them(I think broadcom has such controllers as well) if redhat software cannot do it by itself.
Hard for me to believe anyone would deploy 288TB (minimum configuration - 120TB usable so a considerable overhead) of storage and not have some amount of caching from flash involved. The nature of the system(likely aiming for lower cost) doesn't strike me as one that would be all-flash (also no mention of deduplication or compression, the latter being pretty nice to have for any NAS system).
The design seems more suitable for the content repositories, perhaps redhat is just trying to make their system appeal to a wider audience by throwing a "general" use case configuration in there.