What aspect of heavy-lift rocketry do Musk’s congratulations on Blue Origin milestones serve to validate?

The high barrier to entry involved in reaching certain benchmarks.

When Elon Musk offers congratulations to Jeff Bezos or Blue Origin following a significant achievement, such as preparing for the New Glenn launch, these acknowledgments implicitly recognize the profound technical challenges overcome. This validation serves to underscore the high barrier to entry that exists within the field of heavy-lift rocketry. By acknowledging success, even from a direct competitor, it suggests that reaching specific, difficult engineering benchmarks is inherently a noteworthy feat, irrespective of which private entity accomplishes it first or achieves it overall.