HOTOSM Projects: How Is It Possible to Manage Over 100 at Once?

maybe I generalize too much from personal experience, but I really would be more interested in being first to map a given area rather than encountering overlapping building, wrong landuse etc

I am not claiming that this is dine deliberately to harm OSM

I bet that the tiles match how task manager split area into section, so each person mapped separate tile and then noone reviewed outcome of that effort.