I think even SQLite itself wasn't as ubiquitous (edit: it didn't exist) when pg write viaweb. If SQLite wasn't there and my options were basically key value stores, I could as well use filesystem in most cases.
Second, querying the RDBMS has been much simplified in past 20 years. We have all kind of ORMs and row mappers to reduce the boilerplate.
We also got advanced features like FTS which are useful for desktop and mobile apps.
Today it's a good choice to use RDBMS for desktop apps.
> If SQLite wasn't there and my options were basically key value stores
Well, there were "options" other than KV stores - MySQL launched a month before Viaweb (but flakey for a good long while.) Oracle was definitely around (but probably $$$$.) mSQL was being used on the web and reasonably popular by 1995 (cheap! cheerful! not terrible!)
(definitely understand making your own in-memory DB in 1995 though)
Second, querying the RDBMS has been much simplified in past 20 years. We have all kind of ORMs and row mappers to reduce the boilerplate.
We also got advanced features like FTS which are useful for desktop and mobile apps.
Today it's a good choice to use RDBMS for desktop apps.