That's an extrapolation of ID itself, not a basic tenet.
Although the ID advocates believe the designer is their god, ID does not describe he/she/it/them beyond being intelligent. ID is supernatural by implication, not definition.
And I agree, the richness and interdependency of life on Earth makes it implausible that it was designed.
Matthew Greet
Choose Life. Choose a job. Choose a career. Choose a family. Choose a fucking big television, choose washing machines, cars, compact disc players and electrical tin openers. Choose good health, low cholesterol, and dental insurance. Choose fixed interest mortgage repayments. Choose a starter home. Choose your friends. Choose leisurewear and matching luggage. Choose DIY and wondering who the fuck you are on a Sunday morning. Choose sitting on that couch watching mind-numbing, spirit-crushing game shows, stuffing fucking junk food into your mouth. Choose rotting away at the end of it all, pishing your last in a miserable home, nothing more than an embarrassment to the selfish, fucked up brats you spawned to replace yourself. Choose your future. Choose life... But why would I want to do a thing like that? I chose not to choose life. I chose somethin' else. And the reasons? There are no reasons. Who needs reasons when you've got heroin?
- Mark Renton, Trainspotting.