He wasn't preserving history anymore. He was resurrecting it.

: This update includes support for several previously unemulated or under-emulated games, expanding MAME's already vast library. These additions are a testament to the dedication of MAME's developers and contributors who tirelessly work to ensure that no game is left behind.

Harder to manage if you only want to build a small, curated "Favorites" list. CHDs: The Missing Piece of the Puzzle

Saves the absolute maximum amount of storage space and keeps your ROM directory exceptionally clean.