For vector tiles osm.org this is not the case. They should be generated on the fly from the database to show mappers the current state of the map with minimal delay. Yes, the resulting results can be cached like static files, but much more work is done on the server.
First, my remark is about the impact on the adoption of OpenStreetMap in general, not my personal usage of it.
And second - it did not stop me from doing that, but it was extremely difficult, and took months of effort. I built a tool to set up a server with all the components required to download the data, load it into PostGIS, style it with Tilemill and generate and serve tiles: https://github.com/stevage/saltymill
This is of course great news for OSM. Microsoft also provides Bing satellite imagery for free and helps in the development of some tools.
But a little reminder: in 2013 the Knight Foundation gave 575000 USD for the development of the iD map editor. This is an editor that runs in a browser on the OSM homepage. https://wiki.openstreetmap.org/wiki/ID#Project_history
You can learn more about this in the blog of the developer who develops this tile server: https://www.openstreetmap.org/user/pnorman/diary/403600
p.s. current link to the demo page: https://pnorman.github.io/tilekiln-shortbread-demo