This blog talks randomly about stuff in the Digimon series, mainly explanations for tiny details.
In my opinion, if the first four seasons are connected (in the order Frontier, Adventure, and 02 and Tamers at the same time) Digimon couldn't survive in the Real World when they still were made of fractal code, but after developnig further they can.
Tamers Digimon don't get reborn
I think they would if there was a place like Primary Village or Village of Beginnings. But they haveneither, so it's no wonder they can't be reborn.