I especially want to note that Joost mentions the “SQLite compatibility layer made WordPress Playground possible, has already proven that WordPress can run on a completely different database engine”
And it can. But have you seen it? It’s basically a MySQL interpreter for SQLite.
https://github.com/WordPress/sqlite-database-integration
It’s VERY clever. Incredible effort. But this is a massive hack.
And WordPress has many of these.
There are so many components to maintain now. Layer on layer of tech debt. It’s not great.