Considering H1B visa only allows you to work for the company that sponsored your visa, what you're describing sounds illegal, not just a loophole. I'm not saying they shouldn't do so. And I'm also not saying anything about whether the H1B requirements make any sense. I'm just saying that hopefully they're aware that what they're doing is illegal and may hurt their companies at any moment.
Talk to an immigration lawyer before you try this.
The H-1B visa was clarified to allow for founder sponsorship, assuming you can demonstrate an employer-employee relationship.
To demonstrate an employer-employee relationship you need to be able to show that you can be fired from your company, which is difficult to show if you're the only two founders on the board, and you each own 50% of the company.
I'm not saying it's impossible, but you really want to make sure you talk to a immigraiton lawyer before you try this. And in either case, H-1B visas are very difficult to get at this point :)
This works if you are three co-founders each with 33%, since any two of you could fire the third. (I am also not a lawyer, but this is how I got my H-1B five years ago.)
That said, the fact that the H-1B process is now a lottery - i.e. no matter qualified you are or how good your lawyer is, it's still a roll of the dice - makes it hard to recommend if you actually want any ability to plan for the future.
H-1B also puts more scrutiny on the company, so you'll probably need to have raised money (so you can prove you can pay yourself a market rate salary), have an office, etc.
That would be the equivalent of structuring. It might work, but if USCIS ever investigated you and then found out about this little scheme, you would most likely be banned from the US for 10 years or life.