If you want to hear my take on it after intensively working with dozens of different databases in real-world projects over the past ten years: It is because th

If you want to hear my take on it after intensively working with dozens of different databases in real-world projects over the past ten years: It is because the additional flexibility of graph databases creates the responsibility to manage the explosion of edge cases, while constraints add safety, documentation of intent and reliability. And while special functions for graph traversal can seem elegant and nifty, I have not come across more than maybe a handful of cases ever that could not have been solved by a recursive CTE or equivalent, slighter complex query in relational databases.