At the end of the day this is all about business. The ultimate goal of Twitter is to make money to its shareholders, that we can chat there is just a business service. Businesses come and go, but people always find a novel way to satisfy their need to socialise.
We had all that AOL, MySpace and dozens of other services that are now forgotten, and they all had their own little "who blocked whom" dramas back in their times.
And we had Usenet, IRC or Wikipedia all that time.