Two letters TLD like .io are ISO country codes. Catalonia’s .cat is a generic TLD in comparison. Since .io stands for the British Indian Ocean Territory and Chagos Island isn’t going to be ‘separate’ anymore by becoming part of Mauritius, IANA’s logic is that the ccTLD has to be retired. That .su is still around after the collapse of USSR isn’t a valid argument for them.

They probably did that to prevent “concerned citizens” from attacking their property.

The early internet also had personal website vanishing or being abandoned all the time. Static webpages don’t need constant maintenance but it’s more noticeable when it’s a community.