Iceblink is capped at level 50 which may have been necessary at one time, but now just means no on ever uses it. Removing, or at least greatly increasing the cap, would give players more options for usable legendary gems.
Support Monks say hi. Not only do they use it, they often deliberately use them at Rank 25 rather than Rank 50, because they want to apply the chance for mobs to be critically hit, but not slow them too much, as this makes moving mobs into position harder.
The rest of us who don’t play support monks say hi. Support monks can still use it at level 25 even if there’s no level cap for that gem or the cap is higher. There’ no reason to not allow people who want to level Iceblink past 50 (me included) do so.