I'm not sure what/why/when was changed/removed from this webpage; you may want to contact a VMware representative for official statement.
Being a part of the same Cloud Management business unit as vRealize Automation, it is natural that the main focus of vRO is slowly shifting towards more vRA-centric use cases. But the vSphere customers are also important, so those of them who don't have vRA license have an option to separately download the standalone vRO appliance and configure it with their existing vCenter license.