I'm showing tools. How to use it is a decision of each developer. If you get cents from API and you want to show them, there's nothing bad about this extension.

For example, Stripe, the most popular payment processor, uses cents in JavaScript and NSNumber in Objective-C and Swift (which as you say is a bad practice, because Double can be placed in NSNumber container). Node.js can pass cents as API response and here you'll get use case for this extension.

It's just a tool, it can be used right and wrong, for good and for bad.