Or just don't create 10,000 tables.
Well designed, normalized handcrafted schemas can have hundreds of tables (many basic datatypes, many entities with a few many to many relations each).
Then mechanisms that create and copy tables automatically (e.g. by time intervals; to segregate versions or epochs or instances of something important; as snapshots or temporary duplicates or backups) can easily increase table count by two or more orders of magnitude.
There are also plenty of multitenant apps out there that have the same set of tables (with their own data) duplicated across all schemas.