I thought of it as a scam as no G-Sync module was required, as AMD have proven. Sales of G-Sync would have been much lower if consumers were more aware of what they were purchasing. Nvidia, while not alone, play on consumer ignorance.
Wrong sorry, There is a hardware requirement on the GPU side for supporting Adaptive Sync, hardware that's not normally needed on a desktop GPU which is why AMD's first demonstration was using laptops. This is why Nvidia needed a module. AMD had been working on adaptive sync and had built the support for it into their second generation GCN GPUs. It's why Older GCN cards aren't fully compatible with Adaptive sync despite having display port 1.2. And the Laptop standard is why First Generation APU's from AMD have support.
When G-Sync was released, a module was required. This was the only way of getting it to work on NVidia GPUs. I am sure NVidia could probably get it to work on 9 series GPUs if they wanted but earlier GPUs no chance.
As far as I am award Maxwell GPU's can't support adaptive sync, don't have the hardware. Wasn't too sure about Pascal, some people said Pascal cards did, others said they didn't, at least now we know that Pascal does.
Also just want to add that AMD were working on adaptive sync before Gsync launched. Remember the first Gsync monitor was only released 6/7 months before the first Freesync monitor. And that delay was mainly due to following the path of open certification and getting adaptive sync added to the display port standard, which took 7/8 months. So while Nvidia were first to the market, it's completely wrong to say that without Nvidia sync tech would never have appeared. AMD had laid the groundwork. They had installed the hardware needed to support adaptive sync in their cards before the first Gsync demo.
but, don't take my word for it. If you believe the industry expert like Tom Petersen then you also have to believe Robert Hallock. When he was here doing the Q&A about Freesync, I asked him that very question. He confirmed that AMD had been working on Freesync alongside the development of GCN 1.1.