It's more for enterprise gear than anything. For example, enterprise Cisco gear will absolutely reject non-cisco optics, but datacenter gear won't. As an example, the Nexus 9000 line accepts non-cisco optics by default. Granted, those are 10k+ boxes so somewhat high-end but nowhere near the ASR line.

The nexus line being more modern in spirit also helps. Catalysts still reject non-cisco optics without a configuration line afaik.

A good rule of thumb is whether the equipment tries to vendor-lock you in.

Another example that comes to mind is at least one generation of Intel NICs (don't remember if it's the 5xx or the 7xx), where even the open-source mainline (!) driver will reject the optic without a driver argument passed to it when modprobe'ing it.