That's only valid for DAO Tournaments, correct? Or also for third party tournaments?
Not that there are many non-DAO tournaments, but just in case :-D

I like the proposal. The limitation is not that hard, but makes you choose the tournaments that will probably have the best outcome, depending on one's skill- and decklevel. Up to Silver-Level, you don't even have that many options, so there's no barrier for new players.