I think that those coins were pumped with which it was easier to do this. Because traders capitalize on market volatility. For the same XRP, in order to raise the price up, it is necessary to buy out a lot of orders in comparison with Pundi.
Pundi never rose to prices where XRP is currently holding and XRP is still in the game because of Ripple Labs (which actually ripped off its investors behind the scenes) whereas Pundi X has a real use case, a POS product that is already been used in the markets and their buybacks and burns. I don't know why they decided to give away the tokens in a 3 months period (that quick release of the remaining tokens as part of the investors' NPXS staking percentage), but the price fell down due to that only.