What they pioneered isn't the seed accelerator concept, but rather a repeatable model for it.

It's the difference between the idea for a burger bar, and Macdonalds developing a franchise model for it.

YC have always stated that there can be only one YC and that's the global YC. TechStars have the position that they can design a playbook that allows their "magic sauce" to be replicated.

Although they should (as they have done in the past) acknowledge YC's inspiration of their model.

There's also this gem in their title "Funding and Mentorship from the #1 Startup Accelerator in the World"

From the organization that blatantly copied Y Combinator, the #1 accelerator.

Somebody has an inferiority complex.