You jest but it's 100% doable. If I had a spare couple of months I'd build a UI for this on openstreetmap.org.
(How you'd do it: move osm.org to vector tiles, use Maplibre GL as the rendering library, enable users to upload and select their own JSON stylesheet, build some sort of rudimentary sharing facility so you could use others' stylesheets)
(How you'd do it: move osm.org to vector tiles, use Maplibre GL as the rendering library, enable users to upload and select their own JSON stylesheet, build some sort of rudimentary sharing facility so you could use others' stylesheets)