Interacting with durable data storage is actually pretty common.

Perl is modern (-ish? Definitely modern compared to MUMPS) and had "tie" for database access forever [0]

Python's dbm interface also looks like a regular dict [1]. I am sure there are many others, I know we had one "magic dict" in one of my work projects.

It's just that transparent access has some limitations, like lack of transactions, unexpected latency, lack of strong types, inability to only change a single value.

[0] https://perldoc.perl.org/DB_File#A-Simple-Example

[1] https://docs.python.org/3/library/dbm.html