You often want to build your own tiles for specialized applications. Any map schema is a tradeoff -- if you include every feature in every tile at every zoom level so that the renderer can pick and choose what to show, you bloat the tile file size.

The blog post is very light on details. My intuition is that this is primarily focused on powering the map on osm.org in service of people who edit OSM getting to see faster updates. This would be in keeping with their current raster tiles, which are not meant for use in "real" applications.

There are enough technical challenges in rolling out vector tiles with minutely updates for editors on OSM -- in my opinion, they should solve it for OSM first before thinking about committing to a specific schema for public use by other apps.

Still, anything that incentivizes innovation on vector tiles is pretty exciting. One option that could be interesting: provide "fat" builds of tiles that have every feature, and create tooling to do something akin to treeshaking so people can simplify the resulting tiles to only contain the features they need for their use case.