Is it true Ahmadiyya muslims are declared as non-muslims by all other sects of Islam in the world.?

The prophet Mohammad prophesised that muslims in the later centuries of Islam will mostly stray away from true Islam. There will be 73 sects of Islam and only one of them will follow the path of prophet mohammad and his companions. So this is why all the Islamic sects in 1974 gathered together in Pakistan to declare unanimously that Ahmadiyya muslims were 'non-muslims?