But should Redis really be part of that list? I feel like the strongest point of Redis is that it realistically allows devs to forget about any complex relation

But should Redis really be part of that list? I feel like the strongest point of Redis is that it realistically allows devs to forget about any complex relational models living outside of the code logic, like the ones referred in the article. Other "NoSql" databases look like Redis, but the huge difference with the latter are its atomic operations on simple data structures (append, inc, push, intersect, union …). Redis is the only database that I know of that safely allows the developer to deal with relational data in such a straightforward, close-to-programming manner, and still talk with it at a pretty low level (without having to use mapper abstractions). The "data structure server" description probably serves the project better than "key-value store" in that sense.