Because these "string theorists" fail to define their terms and stick with them, like real scientists do, they are able to postulate such crap.

"I know... Let's tell the ignorant masses that gravity is an illusion." Bwahahahaha! "They will believe anything especially if it comes from a "theoretical physicist.""
Bwaahahahaha! "They are so gullible and stupid, they will all think that they can fly." Bwaahahahaha!