This is rejected under 8.2 of the Official List of Rejected Suggestions

8.2 Add a rank above Scratcher or allow users to skip the New Scratcher status
There are three ranks: New Scratcher, Scratcher, and Scratch Team. The only reason the New Scratcher rank exists is to prevent spam, and since it only takes a few weeks to become a Scratcher, bullying and separation are rather minimal. Similarly, the Scratch Team rank exists so users know who is on the Scratch Team; note that Scratch Team members do not brag about the Scratch Team rank. In contrast, there may be division in the community between Scratchers and those with a higher rank, which could also lead to bragging and bullying. This also includes a “verified Scratcher” status where well-known Scratchers get a special symbol next to their name.

Although the restrictions for New Scratchers may seem annoying, they are extremely effective against spam and inappropriate content. For New Scratchers who are wondering how to become a Scratcher or what it means to be one, check out this post. The Scratch Team will not allow any accounts to “skip” the New Scratcher status, even if it is an alternate account of an existing account.

Scratch Premium would fall under this, which is what your suggestion is based off of.

Additionally:

8.7 Digital currency or money blocks
Some form of digital currency which allows you to “buy” Scratch features (with real or fake money) would not really benefit the educational value of Scratch; after all, there is not really anything that you can buy. While there could be features that are only unlockable via digital currency, this does not really contribute to Scratch's purpose of being a programming language available for everyone. However, you can make digital currency in your own projects, if you like, as long as it follows the policy on pretend currency systems.

This suggestion extends to Scratch blocks in the editor which can be used to exchange digital currency. The problem with such money blocks is that many users on the website are young and do not quite know how money works (and most do not even have a credit card account). Users could make projects which require others to pay a large amount of money to play the project. Overall, it adds further complexity to the website and would limit users' access, without any clear benefit towards the educational value.

A very good detailed analysis for why digital currency should not be on Scratch can be found on this post.

Somewhat ninja'd, I'll add that to mine since it's the top.