I have been programming for ~15 years, the majority of my life. Web, mobile, HPC, CUDA, assembly for x86 and ARM, kernel modules, LLVM plugins, and databases… Not once in my career I found the concept of relational databases efficient or relevant. They are frustrating to use, exceptionally slow and generally provide SQLs, or other DSLs, which is the most archaic form of query representation I could think of - not binary and not general-purpose.
It reminds me of no-code development platforms. They may work (not very well) for some super simple tasks, but as soon as you want to do something at least remotely non-trivial, they put more barriers, then provide help. From personal experience, again, I have grown to hate frontend development so much, that have tried a dozen of website builders, before reverting to good old HTML/CSS (plus a bit of JS) every time I wanted to refresh my blog or companies website.
Plus, I wouldn’t immediately dismiss the concept of Graph Databases. If we want to be truly canonical, we wouldn’t create hundreds of columns in our tables, with just a few relations. The ideology is that every unique “type” (in any sense you prefer), should be in its own table, linked with the other “types” in other tables… Then theory ends and starts practice. Try implementing a fast JOIN in a relational database. Then increase the depth to 3, tracing the relations of relations of relations. Even in a non distributed case it is a horror. Both the nested SQL queries and the program that will be evaluating them. Graph DBs are designed to solve specifically that issue really well.
Another point: how “relational algebra” suddenly makes smth superior to anything else? It’s not a Grand Unified Theory of Physics, not rocket science and not even Graph Theory for that matter. The latter being the biggest and most studied branch of Theoretical Computer Science with brilliant theorems being published even today.
Not saying that todays popular Graph DBs are good (they are mostly disgusting), but I would still much rather think of my data as a graph, than a table with some foreign keys