http://www.uesp.net/wiki/Lore:The_Heartland_of_Cyrodiil: "My studies indicate that the use of the phrase "endless jungle" to describe Cyrodiil appears to be an error in transcription."
http://www.uesp.net/wiki/Lore:Subtropical_Cyrodiil:_A_Speculation: "because once Men ruled in Cyrodiil, the local reality changed to meet their needs and wishes. Changed slowly, perhaps, almost imperceptibly, but inexorably—until Cyrodiil became the realm of temperate forests and fields we now know."
Take your pick.
Most of them can't explain it because they never played ESO beyond the beta. Like the OP here, who wrote off the game before it was even released.
The only real "lore-breaking" thing I have found in ESO is the character of Morian Zenas, who was displaced in time.
There is also some very odd dialogs here and there, but nothing critical.
Globally, I find the lore of the game is very good, far better than the lore of Oblivion or Skyrim. For me ESO is the best game lore-wise since Redguard/Morrowind.
BTW, this idea isn't new, as it come from Nu-Mantia Intercept:
The Stones are magical and physical echoes of the Zero Stone, by which a Tower might focus its energy to mold creation.