No, I think it's because the green energy cards do two things, and only two things: Make a ton of energy, and then spend that energy to make creatures bigger
Creatures (26) 2 Pia Nalaar 4 Bomat Courier 2 Whirler Virtuoso 4 Walking Ballista 3 Aether Swooper 4 Maverick Thopterist 3 Glorybringer 2 Captain Lannery Storm 2 Zahid, Djinn of the Lamp Planeswalkers (3) Lands (23) Spells (8) This is a little closer to a reasonable deck
Unfortunately, from there the novelty of defining color identity in this way was beginning to wear off
If you will compare a Shadowless Pokemon card to its Shadowed copy, you should notice that the Shadowless version doesnt have any shadows or dark shadings near the outline of its art box (as seen in the image above)
It shouldnt surprise anyone, then, that Karlov Manor released alongside a variant of Clue, a board game Hasbro also owns