It wouldn't really affect the ability of rich lobbying organizations to reach all members of Congress, though it might somewhat increase how rich such orgnizations would have to be to even modestly effective, though, really, the effective lobbying organizations are already often the ones that lobby at all of the national, state, and local levels and are connected to grassroots (or at least astroturf) organizations that have broad geographic reach, so, really, it probably doesn't change that much at all.
Unless you eliminate the national capital district entirely and put the entire central administration on a constant cross-country tour (remember that Congress isn't the whole of the government), it probably also creates an imbalance in influence through access with those members physically located close to the capital having more influence. Face-to-face meetings still matter for influence (after all, that's what you are trying to leverage by removing a concentration of lobbying targets), but that also applies to face-to-face meetings between legislators and, e.g., executive branch officials, and legislators exert influence as well as being targets of it.
It'd probably work best after a significant changeover in Congress, when there are a lot of freshman reps all dealing with navigating capitol hill. Such a change would be a big power shift from people who have established relationships to people who have fresh ideas.
And the idea is that they'd be using e-mail, videoconference, Google Moderator, or some other electronic means to communicate with their fellow reps. The idea is to build stronger bonds of trust between reps and their constituents than between reps and lobbyist/other reps, so that they actually act like representatives instead of a separate caste.
If those were as effective means of full-spectrum communication as face-to-face meetings, then moving them out of the capital to their districts wouldn't effect lobbyists ability to influence them -- lobbyists can use technology to communicate with members, too.
It's the same reason that Google makes promotion decisions by a committee located on another continent. You want people to judge based on facts and not impressions, so divorce the objective facts from the subjective impressions.