Other commentors already explained the issue with the country domains being sold privately for profit. That doesn’t answer your question though.
IO means input/output. The symbols are also being used as on/off buttons. It points out to something being digital or technological.
For some people it even represents something that’s new or from the future.
It can also mean artifical intelligence or something that’s utilizing artificial intelligence. It’s also sometimes used as a sound robots make in pop culture.
And finally its used by some of the most intelligent and charismatic redditors as a username because it sounds good, minimalistic and is easy to remember.
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