The problem with that is even today life is lived locally. We perhaps can talk to those further away more today but we don't live in their worlds still.
I think that it is far better to be immersed in the world of your everyday existence, to build most of your community there than to try and build communal ties with a few people from many different places. It weakens the ties and lessens the benefits and still leaves one rather isolated.
Wherever I am, that is where I am immersed. That is where my community is, and the people there know me as someone who travels yet still accept me as part of their locale. So you see, I have many communities the world over.
The ties are not weakened because those people understand the nature of who I am as a traveller, and support my choices. If you are someone like me who believes that relationships transcend distances, then it's a no brainer. It's true that I can't be in contact with everyone at all times or know what is going on in their life at all times, but that would be true even if I were still living there... and I know that if I were to appear in any given community again, I could easily pick up where I left off.
For you, your neighbour is on your street. For me, my neighbour is in another country. You walk down your street. I take a flight. The only difference is the scale of the experience.
I think it really depends on the person and on the situation. Again, you are generalizing. I've met travellers who are extremely isolated people because they have led a nomadic life and have not made sincere attempts to make connections with the people in the places they go. They are the loneliest sorts. For me it's kind of the opposite... I feel a sense of community on my entire planet because of everywhere I have lived.
For instance it is far easier for a strong, community centred village or block to resist a state or a corporation than people isolated all over the country(or world.).
I think this example is more applicable to statehood, which is not really the focus of our discussion.
I think these divisions are often good things. I'm a very particularlist man, I don't believe breaking down borders is often a good thing.
Division can be a good thing, in fact it is necessary to a degree for good gov't. Mass man is not a route we should go down any further.
In terms of allocating resources and maintaining heritage, I think boundaries can be a good thing... but when it creates mental divisions of "us vs. them", I find them extremely limiting. This is just the phase of social development that humanity is at though. Mine is a generation in the newly globalized era where transportation and communication between nations is growing.
I think globalization has worn down the borders a bit, and there are pros and cons to this. It's the pros that I'm really taking advantage of as part of my life experience.