+1 we use SQLite in our BI tool to keep information about user accounts, data sources (cubes) / reports configs, access control rules etc. SQLite works like a charm even in cloud version where we have > 6,000 registered user accounts.
Managed SQL services for SQL variants are readily available and fairly affordable for applications which do not have access to such shared service layers .
It does not mean that SQLite has no place I love using it in native applications and mobile apps, however multi-user web applications is perhaps not one of them, even concurrency is not a problem