I agree with everything you'd said, but, to be fair, we're talking about different things. My claim was not about the complexity of problems, but the scaling of hardware -- which, as far as I know, scales sublinearly. This means that doubling the size of your computing cluster will allow you to solve the same exact problem less than twice as fast; and that eventually you'll hit the point of diminishing returns where adding more machines simply isn't worth it.
You're saying, on the other hand, that doubling your processing power will not necessarily allow you to solve problems that are twice as interesting; in most cases, it will only allow you to add one more city to the traveling salesman's itinerary (metaphorically speaking).
If I understand the Singularitarian argument espoused by many members of this community (eg. Muehlhauser and Salamon), it goes something like this:
I'm in danger of getting into politics. Since I understand that political arguments are not welcome here, I will refer to these potentially unfriendly human intelligences broadly as organizations.
Smart organizations
By "organization" I mean something commonplace, with a twist. It's commonplace because I'm talking about a bunch of people coordinated somehow. The twist is that I want to include the information technology infrastructure used by that bunch of people within the extension of "organization".
Do organizations have intelligence? I think so. Here's some of the reasons why:
I talked with Mr. Muehlhauser about this specifically. I gather that at least at the time he thought human organizations should not be counted as intelligences (or at least as intelligences with the potential to become superintelligences) because they are not as versatile as human beings.
...and then...
I think that Muehlhauser is slightly mistaken on a few subtle but important points. I'm going to assert my position on them without much argument because I think they are fairly sensible, but if any reader disagrees I will try to defend them in the comments.
Mean organizations
* My preferred standard of rationality is communicative rationality, a Habermasian ideal of a rationality aimed at consensus through principled communication. As a consequence, when I believe a position to be rational, I believe that it is possible and desirable to convince other rational agents of it.