This causes the whole materialized view to update. If the underlying query is complex (which it usually is - otherwise you would not need the view), you often don't want to rerun it for every update.
With the separate tools the idea is to stream the incoming updates and keep the materialized views up to date all the time.
How does it know which rows would be affected how when we have something complex? Even better: Is there a detailed proposal or a paper to allow me to gawk at the intelligence of other people? :)
This is likely because the author blocks access from non-Western countries, you're likely located outside the West (I am as well, and had to use a VPN to access it).
With the separate tools the idea is to stream the incoming updates and keep the materialized views up to date all the time.