Need feedback : Discount coupon code sharing app

I need genuine feedback on my app idea.

Idea:

Every now & then when we make any online payment from payments app they give us some scratch card which contains coupons for some random brand.

We as a user not every time will avail those coupons because of two reasons:

We are not interested in that brand.

We don't want to buy that brand's product at this moment.

But, somewhere some person must be thinking to buy the product of that particular brand, so why not there is a app where people can request coupon code of any brand and someone who has the discount coupon of that brand - he reply to the request with that coupon code.

This way we as a consumer will always have the discount coupons for the brands we want to buy.

The consumers will get discount & brands will get repeat customers. It's a win-win for everyone.

A coupon code sharing platform.

What do you think about this idea ? please let me know your honest comments.