You're wrong. The CC-BY is less open because it gives publishers the option of adding more restrictions, i.e. they can restrict what would otherwise necessarily be open content under the OGL. If you create less open content, then that content is restricted; hence the license is less open.
So, if I understand this, you are saying:
Under OGL - Product A releases some OGC. Product B uses that OGC and has to release their own.
Under CC-BY - Product A releases some open content. Product B uses that content but does not have to release it's own.
So therefore OGL is "more open" than CC-BY because of it's viral nature and forcing a chain of open products?
That is true that the OGL encourages a chain of openness that CC-BY does not (but CC-SA does), but also that is
not the standard definition of what makes a license "more open" in general conversations. When discussing copyleft licenses, I have never heard the "openness" of a license defined that way. The standard definition of how open a license is looks at the
product/content being licensed not some vague, general community they create or not, nor at hypothetical chain of derived products. It looks at the licensed content and only the licensed content.
CC-BY Product A allows for the widest range of uses, and is therefore more open in the way that nearly everyone uses the term. The content licensed by CC-BY is nearly as unrestricted as it can get. That licensed content can have no further restrictions placed on it. So it is the most open content (aside from public domain, etc.).
If you want to talk about how "viral" a license is, then OGL and CC-SA are far more viral, but only because they place restrictions on the use of the content that CC-BY does not.
Regardless, the bottom line is that you are correct that the OGL forces/encourages a greater community of open content, just you are applying a label to it that others do not. Typical definitions call that aspect how viral a license is, not how open it is. You aren't wrong, just using words differently than they are traditionally used.