Not necessarily the reason here, but to answer your question: "would there be any other reason?" Another reason is backend constraints. Adding another server m

Not necessarily the reason here, but to answer your question: "would there be any other reason?" Another reason is backend constraints. Adding another server might simply cause more pressure on backend systems like a database. So they can't simply add more servers, as then the additional load on the database might cause that to crash, and result in even longer downtime.