Magic is sufficiently tempo driven now that seven mana is rather a joke and only usable when you have nothing else to do in the end game
Also the archetype has a lot of Spells and Traps that can make up for their relatively weak attack power such as Harpie's Feather Duster, a reliable Spell card that ANY deck can use to wipe out the opponent's backrow, Harpie Lady Phoenix Formation which can destroy monsters depending on how many Harpies you have and Hysteric Party which can Special Summon as many copies of Harpie Lady from your graveyard as possible
The gist of the Red Eyes deck revolves around the Joey's signature Red Eyes Black Dragon, and you'll have a ton of cards to quickly get it out on the field through Special Summon (Red Eyes Baby Dragon, The Black Stone of Legend, Return of the Red-Eyes), and keep it out there, along with other Red-Eyes cards
The best way to get it confirmed for authenticity if youre having doubts is to use a grading service
Lastly, if you have highly-valuable cards in your Commander decks and Cubes, I recommend double-sleeving
In online Yu-Gi-Oh games like Duel Links , several of the Harpie spell cards are on the limited list, which means the player can't add multiple copies to the deck for a higher chance of drawing