To be fair,
@Fabulous50s makes a solid design point - that a wear item such as a belt should not be held captive internally. It would seem as a maintenance item that it should be reasonably accessible, and internal to the engine isn’t. It basically starts to suggest the life of the engine is as good as the belt. perhaps our belt tech really is this good, but it’s still … a bit crazy.
one note - I’ll bet this is a pressure or volume or bypass modulated oil pump - which probably doesn’t command full pressure, and thus force against the belt, under most driving conditions. That may also be factored into design life. Has anyone seen a 2.7 in marine use where it’d be hammered all day, every day?