The resolution requirement (whether =10ns or <=10ns) doesn't force a 100 or 100+ MHz clock.  Only the >=10 MHz update rate forces a 10 MHz clock - which is a pretty modest requirement for OS-A-class systems.  (As a side-note, most any DDR interface or high-speed I/O interface (e.g. USB, SATA, PCIe/NVMe) will want significant clock frequencies supplied to them.)

 

Platforms shouldn't mandate specific software execution performance requirements, but a platform spec may - in the interest of ensuring functionality doesn't have horrible performance - choose to mandate certain qualitative things.  For example, a  more application domain-targeted platform may choose to disallow trapping and emulating of all misaligned data accesses.  (The "Embedded" platform, as a rather basic very "broad" platform, doesn't do this.)

In contrast, mandating that a system has certain hardware capabilities, like a RISC-V standard interrupt controller with at least X number of priorities, or time with some minimum resolution and update rate, is ensuring a form of functionality.  For example, an Automotive or Mobile platform may be unhappy if the update rate and resolution are only 10 ms / 100 Hz.

Greg