This is the first claim I've ever heard that Mini-B is "far more robust" than USB-C. Mini-B is legendarily breakable, both from a pin standpoint (really low lifetime insertions) and from a physical one (the port profile put a ton of strain on the device side). Micro-B was created to resolve those problems, and did a decent job through the latching teeth on the back, but has fewer pins available for advanced connectivity and no room to add them in a backwards-compatible way. Even for small devices, the additional pins are beneficial for standardized high-rate charging via USB-PD.

Both Micro-B and USB-C are similarly rated for robustness.