That is harsh. And I think incorrect. You should perhaps not accuse people of that which is unethical and perhaps illegal without a bit more support.
While it is true that one could produce products based on WotC mechanics legally, in theory, the practice involved a great deal of work and risk - if you did it incorrectly WotC would have been within rights to come down on you and your product like a ton of bricks.
In the OGL, WotC convinced people to sign a license that allowed them to make a product with far less risk, and with fairly clear guidance on what would be seen as allowable use. And they effectively allowed this in perpetuity.
That isn't a scam - that's cooperative business. There's no misleading or misinformation here that suggests any "scam".
Yeah, I totally agree with you on all points, but for the sake of argument, let's look for just a moment at the things you could not do without the OGL.
You could create your own version of the PHB, but it could not copy any text verbatim from the 3rd edition PHB because that would have been a violation of copyright.
You could create a module, campaign setting, or what have you that uses public domain monsters, but you could not copy stats. For instance, you could probably get away with:
Orc (5): hp 6, but if you want to include the statistic for the orcs, or even derive them from the MM, then you're out of luck.
You could not use any monsters that originated in the D&D game. Just page through the MM and figure out which monsters are from myth, public domain sources, and which ones originated with D&D. Now eliminate everything that originated with D&D.
You could not include anything that would indicate compatibility with D&D.
There's more than just that, but the bottom line is that without the OGL, most publishers considered making their own compatible stuff too risky, and for good reason. Back before the OGL, I created a campaign setting that I released for free over the internet, and I included no game mechanics at all just so that I could avoid the potential legal pitfalls.