This seems obvious to me, as there'd be ten times more computational resources.
No, it is because the probability of arriving to a correct answer increases when there are more members in the group, but only when the individual probability to arrive to a correct conclusion is higher than 50%. Group of smart people is smarter than an individual. The opposite is true too. If the individual probability is less than 50% then the group of people is dumber than the individual.
The answer must also be within all of their domains of expertise for the 50% to have any meaning. You can’t have a “room full of smart people” as you’ll just arrive at suboptimal outcomes because your consensus relies on the lowest common denominator of understanding, which between experts in differing fields can be pretty low.
In the context of Condorcet's jury theorem, the percentages refer to the chance of voting for the correct outcome. Think of a legal trial and there is no ambiguity about the meaning of "50%" is.