The only real difference between SQLite and something like Postgres or MySQL is that Postgres and MySQL bundle a networking layer on top of their embedded DB engines.
If you are worried about high availability, chances are you too are building a networking layer on top of a database, so what do you need two networking layers for?
Do people build their own networking layers above SQLite (besides for fun)? If you’re doing that, then you need to build some kind of replication story. At that point it makes sense to just use PG or MySQL
Unquestionably. Web apps and the like which are little more than networking frontends to a database are probably the most common type of software written these days.
Ah, we’re talking about different things. I took “network layer” to mean something like the ability to connect directly to the database over the network, not through some shim application.