Raccomended system requirements

I’m reading this link to the documentation:
And I don’t understand if the requirements is really so big for 5000 users:
4 FronEnd Server 4 Sockets 64GB Ram
4 DBServer 4 Sockets 128GB Ram.

Is there an elastic solution implemented for example in AWS?

And What about the db-loadbalancer? The nextcloud sw don’t be able itself to switch queries to the master or to the slave?

Thanks for all your suggestions