The problems with the technologies is that the "robust database" guarantee is often highly dependent on the currency mechanisms. They unfortunately go hand-in-hand.
Remove the currency from a blockchain and you have a merkle tree. (To be even further unfair, considering currencies in aggregate, blockchains are always a merkle tree. How many forks of Bitcoin are we up to now?)
Merkle trees are incredibly useful, and yes a sort of robust database. I use git every day, but I have to respect that git branches and git forks are real phenomena and coordination of branches/forks always a real ongoing concern when working with git. Not a lot of institutions want a "robust database" which is easily branched/forked. You still need a coordination engine to keep the tree a "chain" somehow. The currencies for better and a lot worse (given how many seem isomorphic to scams) are the coordination engine that still seems most (distributed/transactional/"robust") useful to making a "blockchain" out of a merkle tree.