The etymology of "rez" is a textbook case of linguistic clipping. English speakers naturally streamline polysyllabic words when those words become central to repetitive, time-sensitive actions.
In a high-intensity battle royale, taking three syllables to pronounce "res-ur-rec-tion" can cause a team wipe. A player has roughly 1.5 seconds to communicate an action before an opposing squad pushes their position. The single-syllable "rez" carries maximum information with minimal acoustic friction.
The same phenomenon explains why restaurant goers avoid the five-syllable mouthful "res-er-va-tion" in casual text threads, and why early computer scientists dropped the four syllables of "res-o-lu-tion." Language cuts away the excess to keep up with human speed.
