Let me offer a bit of an explanation for what he's saying, because I'm the one who actually suggested it:

Has anyone seen Sliders? If so, then me mentioning that show explains everything to you simply enough. If not, then the plot of Sliders is strikingly similar to this RP. A group of people dimension hopping through different versions of Earth. The only difference is that the Sliders cast all originated from the same Earth (which for the purposes of setup was the default "Real" Earth, as in identical to Real Life) whereas our cast of characters was plucked from multiple Earths. Us all starting on the same Earth is meant to give us a more timely and structured beginning. Less time is spent searching for and gathering us together, and whatever version of Earth we start on is considered the de facto "default" Earth that serves as the baseline for which all the others can follow. Another thing Sliders makes regular use of is having the characters run into different versions of the same people from time to time, including themselves. I suggested framing the story this way because Letter told me he wanted to not have any fictional worlds and have them all simply alternate histories with no fictional basis (so no Panem, no Madoka Magica, etc).

I do understand such a suggestion requires some character tweaking and rewrites for most of us, so I don't blame anyone for being apprehensive to the idea.