I think the "both is good" argument for Valki and Tibalt is that they'll be good together but there's no added value
Even slight imperfections, like slight creases or scratches, can reduce the value
(Japanese Yami says this is badthe Big 5 will target Anzu and Shizuka

Aeromunculus Aquastrand Spider Bebop, Warthog Warrior Black Tom Cassidy Cloudfin Raptor Crustacean Commando Cytospawn Shambler Donatello, Turtle Techie Drelnoch Elvish Aberration Evolution Witness Flamewave Invoker Foe-liage Glintwing Invoker Hand That Feeds Helium Squirter High-Flying Ace Ice Cream Kitty Incurable Ogre Insectoid Exterminator Jennika, Bad Apple Big Sister Leonardo, Big Brother Michelangelo, Game Master Molly Hayes, Runaway Mutant Surveyor Mutant Town Musicians Nantuko Vigilante Null Group Biological Assets Prehistoric Turtlesaurus Punk Frogs Putrid Pals Quicksilver, Pietro Maximoff Raphael, Tough Turtle Rocksteady, Crash Courser Simic Initiate Singe-Mind Ogre Slithering Cryptid Smokespew Invoker Sporeback Troll Squirrelanoids Starlight Invoker Stockman, Mad Fly-entist Stonewood Invoker Twisted Abomination Vegetation Abomination Vigean Graftmage Vigean Hydropon Wirewood Guardian Wolfsbane, Highland Hero

Now, not all game pieces are created equally, and some of the more divisive ones have become the poster children for Stax and thats before I even get into how people are more than willing to throw taxing effects under the same bus