In consideration for agreeing to use this License, the Contributors grant You a perpetual, worldwide, royalty-free, nonexclusive license with the exact terms of this License to Use, the Open Game Content.
Notice that section 4 says nothing about acceptance.
I'm not sure what you mean by "consequential" - but the exchange of consideration and the acceptance of the offer are simultaneous. If they are not, then no contract arises. Suppose someone says "Do you want to buy my bike" (invitation to treat) and I think about it for a few minutes and say "OK, sure, here's $100" (offer) and then they say "Yeah, OK" (acceptance), we have offer, acceptance, consideration - a promise to transfer the bike in exchange for a promise to pay $100 - and hence a contract. The promises to transfer and to pay become binding at the moment
the contract is formed by the vendor's acceptance of my offer of $100.
In the case of the OGL, at the moment a would-be licensee uses the offered material they accept the offer, the consideration passes (ie the grants of licences from licensors, and the duty on the licensee to uphold their obligations under the OGL).
Consider the following scenario, in which each of A, B, C, D and W is a corporation, and all agreements are on the terms set out in terms of the OGL v 1.0a.
W licenses its material X and its material Y to A. A publishes a work that contains X and also their own material Z; Z is derivative of X. A's section 15 statement includes W's work and A's work.
W also licenses X and Y to B. B publishes a work that contains Y and also their own material Q; Q is derivative of X. B's section 15 statement includes W's work and B's work.
C wishes to publish a work that contains Z, Q and also their own material R, where R is derivative of Q and X. C does not wish to infringe anyone's copyright without permission. C therefore needs a licence from each of W, A and B. Therefore C enters into a licence agreement with A and B, whereby A and B also exercise their powers to sub-license W's content to C. C's section 15 statement includes W's work, A's work, B's work and C's work. C has been granted a licence by three Contributors (using that phrase as it appears in section 4): W (grant by way of sub-licence from A and B), A and B (neither of these grants is by way of sub-licence - each of A and B is licensing their own work, ie Z and Q respectively).
Is there also a contract between W and C? Assuming W's offer remains on foot, probably yes: C is using W's content X and Y (and thus accepting the offer) and consideration is flowing from W to C (the grant of a licence). If W's has withdrawn its offer, than probably not, as there can be no contract with an offer. Does it matter whether or not there is a contract between W and C? I don't think anyone has yet identified such a scenario.
B winds up (ie ceases to exist). D wishes to publish a work that contains, inter alia, Q. D does not wish to infringe W's copyright - hence D needs a licence (Q is derivative of X, which is W's material). D therefore takes up C's offer, and receives a licence in respect of X (a sub-licence) and in respect of Q (a sub-licence). Is D also in a contract with W? See above. Is D also in a contract with B? No, B no longer exists. Is D also in a contract with D's successor in title to the copyright in Q? To me that seems unlikely: D probably doesn't know who that is, and that person is probably not making any offer. Does that person have any complaint against D for copyright infringement? Not that I can see: B granted C a power to sub-license in respect of Q, and nothing seems to have brought that grant of power to an end (maybe there is some such rule in the copyright law of a particular jurisdiction, about termination of licences upon expiration of the copyright holder - if so, I don't know about it).
I don't see where any contradictions are occurring.
There is no "being made to grant". There is simply "granting", that is, the coming into being of a licence that permits a licensee to use the licensor's property. Some grants of licence are effectuated by the owners themselves. Some are effectuated by way of sub-licence. As per the example above, the way the OGL is designed to work - ie creating an ever-expanding network of contractual licence agreements - may mean that the act of sub-licensing also generates a licence agreement directly with the head licensor. But that is not essential: this is why the better legal view is (in my view) that W's withdrawal of its standing offer to license its work will not affect the existence and the possibility of expansion of an OGC ecology which has that work at its centre. Because the powers to sub-license, and thus to generate licence grants from W to new parties in respect of that work, endures.