"Lotus Notes is not a RDBMS and never has been."
Exactly. It was a poor man implementation of a database, and was barely OK for some simple applications. The fact you had to use LotusScript and very poor development tools didn't help.
The company I was working for in the 1990s did Notes development - but most customer soon asked for RDBMS and far better frontends - the same fate applications built on dBase, Clipper, FoxPro and Access suffered too - it was far easier to consolidate data inside an RDBMS and access them from different tools.
That's why the RDBMS market thrived, and Notes went down the hill. Nobody went the same path, and for very good reasons.
I'm just surprised the Wizard of Ozzie got so much credit, and got MS money too for delivering nothing again...