It, in my opinion, is absolutely awful feeling to join in late to a match only to have the misfortune of having something stupid like less than a quarter of your health available to you because of dumb AI taking loads of punishment throughout the level.
It feels awful to be practically punished for an AI’s mistakes by having not enough health to survive even a single scratch from ANYTHING from the very moment you load in, and it makes it so that players are less likely to join lobbies where the mission has already started as you’re taking a gamble as to whether or not you’ll have a good amount of health or be an inch from death’s door.
To be fair, for all you know, a player just left before you joined. You’re just taking over a player slot, it wouldn’t be fair to get a full reset on join.
A player who joins in a match late will have their health increased to at max 25% of their total health pool upon spawning / taking over for another player or bot.
To get the effect a player must join an entirely new group, any attempts at joining a group you were already part of before leaving / disconnecting from a mission will leave you at the current health value of the bot / player before you (same as it is now.)
That way players who join in late can have a better fighting chance, and friends who play together can’t abuse or exploit the system nor can anyone else with the same sort of goal in mind.