Sexual selection is quite a different animal, but we can't take as a given that sexual selection increases as natural selection decreases. It might; I just don't know any reason that it would. And there are reasons that even sexual selection would diminish--for various reasons, I don't think anyone today could have nearly as many children as Genghis Khan did.
There is the distinct possibility that they affected the chance for others to reproduce or survive. So you are right about their individual evolution, but they were likely part of group or species evolution.
In bees and other hive insects this effect is most pronounced, as there are only only a few individuals in the hive that can reproduce. But with only them, the hive would die out, so the rest is useful from an evolutionary standpoint.
I find the idea of a stable rate of evolution curious. With respect to your argument, we are in agreement: there is reason to suspect that evolution as a reaper has become more tolerant; on the flip side, I'd argue that genetic diversity is increasing, as a consequence of with an unbridled phase of expansion. In this sea of diversity, the genetic victor exists, to be revealed during some future event of punctuated equilibria.