Gift cards are very limited. The tech behind gift card usage is extremely insufficient. Things like checking balance is often not even possible with a public API layer.
Tokens are very limited. Things like checking the balance is often not even possible for a nontechnical user (i.e. the vast majority of users), who doesn't care about API layers. You can implement software to make this friendlier, but you can do that with gift cards too, and the gift card technologies are already mature.
Not only is this a solution in search of a problem, it's a solution which hasn't found a problem, and is being shoehorned onto problems it actually exacerbates. If you're running a business, the last thing you want is for your business' systems to be decentralized, because that means you don't have control over them. There's literally only downsides for the business.
This would also enable seamless gift card exchanges. Currently secondary markets exist for gift cards, but they take ~10% margin to account for the high fraud risk, holding time, etc.