I understand what you're saying, and I've heard that answer before, repeatedly; and I don't buy it.

Suppose we were arguing about the theory of evolution in the 19th century, and I said, "Look, this theory just doesn't work, because our calculations indicate that selection doesn't have the power necessary." That was the state of things around the turn of the century, when genetic inheritance was assumed to be analog rather than discrete.

An acceptable answer would be to discover that genes were discrete things that an organism had just 2 copies of, and that one was often dominant, so that the equations did in fact show that selection had the necessary power.

An unacceptable answer would be to say, "What definition of evolution are you using? Evolution makes organisms evolve! If what you're talking about doesn't lead to more complex organisms, then it isn't evolution."

Just saying "Organisms become more complex over time" is not a theory of evolution. It's more like an observation of evolution. A theory means you provide a mechanism and argue convincingly that it works. To get to a theory of CEV, you need to define what it's supposed to accomplish, propose a mechanism, and show that the mechanism might accomplish the purpose.

You don't have to get very far into this analysis to see why the answer you've given doesn't, IMHO, work. I'll try to post something later this afternoon on why.