Why three carriers create a usable force

Would three completed Kuznetsov-class carriers have made a meaningful difference?

Yes. Three ships would make one available while the others train or refit and would sustain a larger pool of carrier specialists.

Carrier numbers are an institutional problem as much as a hull count. With only one ship, a long refit can hollow out air-group and engineering expertise. Three hulls make it possible to keep one carrier available while another trains and a third undergoes deeper maintenance. They also support a larger pool of pilots, deck crews, engineers, instructors, and spare parts that can preserve carrier knowledge between deployments. The Soviet or Russian state would still need to afford the operation and maintenance of all three, rather than merely complete their construction.