See, your question is an excellent example of how little the mainstream tech understands the WP ecosystem: In any WP site, any user that uses a feature is some

See, your question is an excellent example of how little the mainstream tech understands the WP ecosystem: In any WP site, any user that uses a feature is someone who 'saves content'. They don't need to be an editor. The average user that is commenting on a WP blog, the average customer that is using a WP ecommerce site, the directory user that is bookmarking local lawyers in his area - all of these send write operations to the db. Because all of those features are represented as either custom posts in the database. If a plugin does not use the WP post system, then it still writes to its own tables. So basically any write action taken in a WP site is very likely a 'post'. Its confusing, so just take the word 'post' as 'data type'. The blog posts in a WordPress site are just data with the type 'post'. WooCommerce products in a WP ecommerce site are just data with the type 'product' and so on. Therefore, even in a middling WP site with ~1 million unique views/month, you WILL have at least hundreds of users hammering the database with the actions they take. When you go one level up, things get even more complicated: There is a WP feature called 'Multisite'. This allows you to provide an infinite amount of WP sites over just one single WP installation by sharing the database and the main files. A lot of big WP sites function like this, including the WordPress.com service that Automattic provides. (50% of all WP sites are there, so 25% of all world's websites). Which means that in such a Multisite WP installation, there will be at least tens of thousands of site owners, whose blogs, e-stores or sites are serving hundreds of thousands of users at the least. (For smallish WP hosts, nonprofits, communities). This means that yeah, you will be facing write operations that are much more than 1000 times per second. ... Regardless, one minor performance situation is not the argument that makes it infeasible to introduce SQLite or any other db engine. The compatibility is king in WP ecosystem - ecosystem-wide and backwards. Just like in any ecosystem that has been able gain and serve a large user base on the Internet.