O(n) describes limiting behavior as n → ∞. In the process of getting to infinity, you will necessarily cross capacity limits.
Cache-Oblivious Structures I, MIT, by Erik Demaine
https://www.youtube.com/watch?v=bY8f4DSkQ6M
Closing the Gap Between Cache-oblivious and Cache-adaptive Analysis
https://www.youtube.com/watch?v=eB_UH7tLomw
Analysis of Recursive Cache-Adaptive Algorithms, Andrea Lincoln, 2015 (thesis)
http://dspace.mit.edu/bitstream/handle/1721.1/100630/9332274...
Why are you saying 'we' in your comment?
computational regime
I think you mean environment instead of regime.
the said “infinite” store
None of this is true for basic O notation, it's just what exponent the algorithm carries on the number of elements.
Big-O notation doesn't even have to do with this article, it's just showing that memory access isn't strictly constant. This all seems like you're trying to argue something that isn't a part of this thread and I'm not sure what that is.