Mind Web Tree Angular Developer interview questions

Total 4 rounds of interview for Angular Developer Role, All rounds are face to face(offline). Question related to Angular and JavaScript. But my experience is very bad, my all rounds clear perfectly after that they ask for documents for verification, i gave all required documents after verification they ghostly not giving any response after 5 6 days they said that we stop hiring for Angular Developer. My question is simple that why you waste candidate time and down the moral firstly you call candidate for first 3 rounds face to face if you have to stop hiring for that position why you call candidate for final round with CEO. Please don't waste candidate time if you don't have any vacancies.