While its ability is costly, it provides a powerful late-game threat that fits well in counter-focused or fungi-themed decks
That being said I actually think it's quite a small concern and think that in the right deck Dark Tutelage can be great
When a card rotates out of the format or gets power-crept by a new release, the price usually drops back down
Now, lets take a deeper look at one of the biggest names in the industry, Professional Sports Authenticator more commonly known as PSA
0.888 per cent (5th card probability rate, regular pack) Full Art Venusaur EX, Full Art Articuno EX, Full Art Gengar EX, Full Art Mewtwo EX, Full Art Marowak EX (Mewtwo Pack) 0.275 per cent chance: 0.055 per cent per card (4th card, regular pack)
This keeps them on the back-foot and dancing to your tune until you're ready to deploy characters with 'Evasive' (meaning they can't be challenged unless the other card has Evasive too)