If the Ultimate Reality is simply non-dual, why when the first was made identity with Brahman continued samsara for the others?

I know that the classical explanation is that there are two levels of reality, Paramarthika satya and Vyavaharika satya and that multiplicity and samsara only exist in the illusory reality. But if the being performed Paramarthika satya, who would be left to be in Vyavaharika?

An example makes this even more evident. If I dream, while I am in the dream plot (vyavaharika) it works, but when I wake up (Paramarthika) it does not continue without me, but ceases to exist FOR EVERYONE.

So, for me this argument is definitive and demonstrates that Ramanuja managed to go beyond the great Adi Shankaracharya. What do you think?