Except those pioneering web-services companies which provide AGPL code for their services but require copyright attribution to contribute to the main tree and at the same time maintain a proprietary paid version. In this case, they essentially prohibit anyone else from running a similar business - since the founders will have the leading edge on the 'main fork', and competitors can't maintain their own private paid versions, business competition will always be playing catch up to them.

This particular use case is where the implicit dualism of GPL software-centricity (vs people-centricity) falls apart/becomes absurd in my opinion - yes, the OSS version of the software is 'always free as in libre', but it is also always controlled by a creating entity who is using the license to create a defacto monopoly on it's commercial use, so the people are always beholden in some sense to the original code owners.