The point of disaggregating your replicated database is you can scale your app and db tiers independently. Typically you only want to have a handful of database

The point of disaggregating your replicated database is you can scale your app and db tiers independently. Typically you only want to have a handful of database replicas (e.g. to failover after your primary fails), especially if you want strongly consistent replication. But your stateless app tier may require many more servers.