Can't purchase the first reserved instance?

The answer from support/service teams, citing:

"Our service team informed that No Upfront Reserved Instances (RIs) can pose a significant billing risk to accounts that are lightly used or are new, as they're a contractual obligation to pay monthly for the entire term of the RI. For this reason, lightly used accounts and new accounts are unable to sign up for No Upfront RIs until a successful billing history is built with us."

In other words, the mentioned cryptic error message meaning was like this: "You are paying too little for our services; thus we have to restrict access to certain products. Since we only are computer-friendly, our response was meant for automated processing. We hope our support team assisted in translating the error into human-readable form".

Something like that.

Actually, I would prefer that the above be stated in plain text both in docs and in response from console - instead of forcing me to waste time of both myself and of support/service teams to decipher the error code.