I think the article falls into a pattern of web developers demanding too much control. Fine grained control belongs to the users. The browser is a User Agent,

I think the article falls into a pattern of web developers demanding too much control. Fine grained control belongs to the users. The browser is a User Agent, after all. Users may have their computer configured to display text bigger or smaller than normal. They may have blocked ads. They may have disabled autoplaying video. They might be using Flux or Reader Mode. They might be sitting on a couch, projecting a 6ft image onto a wall. Just size your stuff in px. How many millimeters that works out to is up to the user.