This just means Geekbench isn't good at scaling to multiple cores. It could be the workload or the implementation. If you have the right workload and a good implementation, modern processors do scale reasonably well (all numbers with Threadripper 3970X):

Cinebench R15: 206 single, 7302 multi, 35.4x scaling

POV-Ray: 9:02 single, 0:19 multi, 28.5x scaling

The scaling can be greater than the number of physical cores due to SMT. On the other hand, turbo clocks increases the single-core speed by 10% or more on most CPUs.