Generally you can look at stat based deaths as such (As per 3.5e):
Strength - Muscles cease to function. Heart stops/rendered helpless.
Dexterity - Total paralysis. Heart stops/rendered helpless.
Constitution - No life force.
Intelligence - The mind is gone. The target is a soulless husk. Effectively dead.
Wisdom - Enters a deep, endless sleep state filled with nightmares. Effectively dead.
Charisma - Enters a catatonic state. Effectively dead.
Stat deaths have been around for a while. They used to be an effective deterrent for stat dumping, because if you ran around with only 3 points in a stat, you could easily get stat-deathed especially with stat reductions being more common back in the day.
These days, stat reductions are a lot rarer and generally you tend to get more limited in stat allocation (BG3 puts the minimum you can assign to 8 for example). So it tends to be a more niche mechanic, especially since general usage of it means it does nothing 50% of the time (Given that only even levels of stats provide anything... Taking an enemy from 19 STR to 18 STR does literally nothing).
