Sure, but if the journal publishes too many articles it'll lose prestige. Nature publishes what, 8% of submissions? And that's apparently what they consider financially optimal -- they're a for-profit corporation, they could publish more if they wanted to. I guess the question is just whether this applies equally to open-access and traditional subscription journals.
But Nature doesn't make its living by publishing articles, it does it by selling subscriptions. This requires having high "prestige" so people want to subscribe to it.
If you're just charging for publishing articles, you don't care about whether anyone reads them or about what your "prestige" is, since you don't make any money off of that.
It's true that if I publish a paper it's better for me if it's read and thus cited, but that's much less of a difference compared to published vs not published at all. The entire problem starts with authors not being incentivized to publish a few good articles over churning out as many as possible.
