I've said it numerous times.

Specialization Only should be removed as a lock on recipes preventing people from doing them. Specialist Actions should not exist either. Remove both of those, and make the Specialization Stone confer ALL of the other 21 Cross Class Actions, of the level 15, 37, and 50 variety.

Once the Specialist hits level 70, or goes over 60, the Specialist should gain access to all of the level 54 Cross Class Actions as well.

This would simultaneously remove most of the advantage an Omnicrafter has over someone with only one Crafting class, while allowing them both to actually compete with one another in the marketplace. That competition was the stated goal of the Specialist System.

Preventing people (those with different Specializations) from crafting high level recipes does not provide competition, it eliminates it, which is in diametric opposition to the stated goal of the Specialist system.