SQLite is one of the most reliable codebases in the industry. You're ignoring what the comment says. In an n-tier architecture, both your app server and your database server needs to be HA, because they're servers. With SQLite, the app server is the database server. It's still HA, there's simply one fewer thing to HA-ify.
I don't know what "non-enterprise-ready" means, but it sounds like a selling point to me. The XML can come later.
When the app server is stateless, HA for the app server
is usually a near trivially easy problem to solve though, and a whole lot of web devs are used to treating the database as a black box that they'll treat as always up so I get the fear and uncertainty of suddenly having the HA setup interfere with "their" domain.
Coming at it from a devops angle, I'm used to being the one to have to deal with the database HA myself, and then having one tier less becomes a lot more appealing, and not really more scary than ensuring any other database setup is resilient.
I don't know what "non-enterprise-ready" means, but it sounds like a selling point to me. The XML can come later.