This question reminds me of an old film called Total Recall, in which virtual vacations replaced physical ones. Virtual travel had/has a lot of advantages, but it is a different experience. Until we live our entire lives virtually, like in another old film The Matrix, we will likely still enjoy travel with our entire body, not just our mind. The OP asked if virtual worlds could help reduce real world pollution though, not eliminate it, and the answer to that is yes.
Consider online education, which has been doing this for a decade or more. More recently, professors at University of Hawaii began teaching holographically to students in American Samoa, interacting in real time from thousands of km away.
The famous Louvre art museum in Paris conducts online tours, allowing people to explore the Mona Lisa and other works from anywhere in the world. And similarly, if you've ever looked at homes and apartments online rather than checking newspaper ads and visiting every one of them, you've saved a ton of fuel, time, expense, and pollution.
So French Couturier makes a good point: virtual worlds definitely reduce pollution. But there is no one answer to a problem as big as human waste. Instead, there are many solutions, and virtual worlds are just one.