Once you begin to cast Ruthless Disposal, no player may take actions until youre done
If your opponents load up their creatures to try to stop you, you can grind them out with Early creatures with eerie abilities, such as If you're looking to change up the deck, you could lean it away from being so focused on Auras and care about enchantments in general
Theres no shortage of artifacts with high mana values
Theoretically, there could be language triggering off ties or losses, but that doesnt exist (yet?)
The only real drawback is the fact that you put the card on top of your library instead of in your hand, but you can easily work around that thanks to it being an instant
Vendors rarely want to leave money on the table, so the number they list a card at is often going to be on the higher end