The reason is different. When you need to scan 5 million IPs on 22 port is one thing, but 5 million IPs times 100 or 1000, then you simply run out of resources

The reason is different. When you need to scan 5 million IPs on 22 port is one thing, but 5 million IPs times 100 or 1000, then you simply run out of resources and since 99% of people use 22, why bother?