Realistically hashes are used during the development of a game to detect when a file or asset hash changed, and therefore it will trigger regeneration of assets

Realistically hashes are used during the development of a game to detect when a file or asset hash changed, and therefore it will trigger regeneration of assets that depend on it. For some long or slow build steps it is better to rely on a hash changing than the timestamp changing to trigger a build. It can also be used to fetch pre-built data from where it's cached on a server. That's why it should be fast and doesn't have to be cryptographic. Regarding security if you're at the point of someone malicious creating a file on your internal systems you've already lost the battle.