I'm sorry, I was referring to hybrid storage as a technology category, not the hybrid disk drives like Seagate Momentus XT. You're right that a 2-drive hybrid (Fusion Drive) will mathematically be less reliable than a non-hybrid one and that those "hybrid disks" haven't lived up to the hype.
Pretty much every enterprise storage solution designed today is hybrid (SSD plus HDD) or all-flash and includes lots of advanced availability features.
> "Pretty much every enterprise storage solution designed today is hybrid"
By this do you mean simply that there is both SSD and disk storage around, or do you mean that the storage system transparently chooses where to store particular things without the apps having to care.
If you buy an enterprise storage frame there are a variety of mechanisms where as a storage consumer you just see a LUN, but in the backend individual extents/blocks/volumes are tiered in different performing areas.
These systems will transparently "promote" hot blocks to flash or faster spinning disk, etc and demote cold blocks based in usage patterns and policy, without the app being aware.
There are a lot of different ways to do it, ranging from tiering within the array to a storage virtualization solution that can tier data across different storage platforms. In one case I worked on a project where that virtualization tech was used to consolidate 10 data centers to 1, pretty much transparent to the end users and mostly transparent to the folks running apps. (Exceptions were ostly apps that built their own Storage HA)
Pretty much every enterprise storage solution designed today is hybrid (SSD plus HDD) or all-flash and includes lots of advanced availability features.