These decks aren't always able to stop you from just killing them (which is why Tron decks are going for black and white interaction these days)
Even these high prices, however, are nothing compared to the serialized Golden Chocobo cards
Falling Star incentivizes players to physically spread their cards out over a large area in order to minimize the possibility of multiple permanents being affected
Suddenly, Sparksmith killed itself, Pinpoint Avalanche took out your opponent's best creatures instead of your best creature, and that Mythic Proportions your opponent just cast decided to enchant Willbender instead of your opponent's Taunting Elf
A "Gem Mint" 10 graded by trusted experts like PSA, BGS, or CGC can be worth 100x more than a "Near Mint" 7
Each of them has their pros and cons with regard to these effects