Why can't Discord Classic be upgraded to Discord Nitro?

Hello everyone, I would like to offer a feature to upgrade the regular Discord Classic to the full version of Discord Nitro. It’s just my personal experience that I bought Discord Classic without noticing that it doesn’t offer changing the banner on the account, and since I bought it for a whole year, I obviously don’t want to pay another full price for a full-fledged Discord Nitro, I would like to pay extra and upgrade my Discord Classic to a full Discord Nitro.