It's not a new idea. We do it every day. Every act of kindness, offer of help, question, or shared piece of information builds a community around each of us. The real effort comes when we try to do it deliberately and consciously - to not wait for the invitation but to invite; to not wait to be asked but to offer. Rejection doesn't come as often as we fear it might. (though it does still come but if everyone liked everyone that would be creepy...)
Another name for this is networking - building stronger ties with those you know and forging new ones. None of this takes an event, party or large meeting.
Our communities overlap through shared interests, people or projects. We don't have to know everyone directly; we just need to be open to collaborating across shared connections.
Each of us already has a community; fewer of us deliberately fill ours. There is nothing wrong with being deliberate, with being interested in new people, activities, knowledge sources and opinions. Sincerity of interest is the key. Openess and trust in sharing what we know or feel is important. Family, friends, acquaintances - the inner and outer rings of our circles - are the buffers and safety nets of an uncertain world. (thanks for being part of mine and inviting me into yours - I promise to list each of you in my Academy Award speech one day!)