That's not necessarily true:
If the player chooses to reject the qualifying offer and signs with another club, his new team must give up their highest unprotected pick in the next MLB Draft. Top 10 picks are protected. The team that lost the player is then given a compensatory draft pick at the end of the first round and is based on the previous season’s standings.
From:
https://fansided.com/2016/11/10/mlb-...ng-offer-work/