I dont understand why all the policy change happens only when you are due for promotions

Its feels pathetic when you pur sweat and blood for company and perform beyond what is asked for in a role for the company and when its your turn of promotions and increments, the company suddenly brings a promotion policy company wide and tell you that now promotions would be EXTREMELY limited and dont have any high hopes. Its really a roller coster ride when you are fed up of a company, make a switch and then give 200% only to realise that things would have been easier of your skin color was different or you location wasn't India but some developed country in Europe or US/UK. Anyone has any similar views, pls join the rant.