Yes, I disagree ... it never could be, so it still can't be. Or it always could be and it still can be.

Depending on whether you mean plant and equipment and productive capacity, or accumulated stock of financial assets. With the former, the aggregation for the normal purposes was always a polite fiction, while with the latter, it still can be aggregated, its just that people don't like to do it because they don't like what's happening to the total given the "financial obligations that can and will in fact be met" qualification.

Consider modern capitalism as an economic system that allocates its resources by encouraging individual citizens to decide to which group of strangers engaged in productive enterprise to entrust their wealth tokens, they being motivated to do so by a common expectation that the value of the obligations thereby created will become greater than that of the wealth tokens they handed over.

Whatever your definition of "capital", whatever your view of whether it could in the past be accumulated, or will in the future be capable of being accumulated, permanent economic contraction seems likely to bring the end of capitalism as a dominant feature of civilization.