the only culture a person can criticise now, is their own.

Nothing wrong with that, nothing new in that. As the Bible puts it: And why beholdest thou the mote that is in thy brother's eye, but considerest not the beam that is in thine own eye? Or how wilt thou say to thy brother, Let me pull out the mote out of thine eye; and, behold, a beam is in thine own eye? Thou hypocrite, first cast out the beam out of thine own eye; and then shalt thou see clearly to cast out the mote out of thy brother's eye.

After all, the only culture anyone has the kind of expertise to make their criticisms meaningful and useful is their own, whatever that may be.