Without the @ it could be used as an address too. The To: field is unambiguously a list of intended targets, independent of the formatting -- it's unfortunate

Without the @ it could be used as an address too. The To: field is unambiguously a list of intended targets, independent of the formatting -- it's unfortunate that twitter has no metadata and the recipient list needs to be listed in-line with a special syntax. When someone wants to get my attention or directs something they say at me, they use the same string I use to identify myself, my name, not (necessarily) with any special prefixing/enclosing/suffixing embellishments. I am thinking that the domains have less and less importance, and that our data should be more integrated across the web. That a "domain" is something on the RHS of an @ and is the name for something you can "purchase" the right to use is inconsequential. I could just as well purchase a domain that is my name (independent of the fact that there are well-known TLDs that you are limited to purchase under). Domains are just the base-line identifier that we tie a bunch of internet related services to, through the DNS and zone files, there is nothing inherently "domain-y" about them.