How do you know that no one has done it. I know quite a few who have done it with the same employer.
As I stated before, this was a very hot topic back in September. Many people checked with their lawyers and were given the green light to do so.
There isn't much room for intent in laws in USA.
The part of the I-140 that you have mentioned which asks if an I-140 petition has been filed before is not specific to the employer. If anyone has filed one before you need to answer it yes (approved or not approved). One of the reasons for this question is to see if they can transfer the priority date for you or not.
By your reasoning if a person files a labor and 140 with the company and it gets denied for education mismatch or ability to pay and then company files another labor for the person then that is illegal and not within the intent since beneficiary is getting sponsored for a different job now?
When DOL came out with their FAQ that it was one labor per beneficiary, just about every lawyer threatened lawsuits and DOL backed away from their stance. Now they say they won't approve second labor if it is for the same job opportunity in same geographic location.
Not to sound too critical but I've found the people who want to argue this are the ones who are not in position to do this and are afraid they are going to miss their place in line since people are going to jump over them.