Spirit? I don't get why would any serious sweaty PvPer play an extraction shooter in the first place when there are actually competitive pvp games without all that looting and extracting bullshit available. Some of them even for free and they are all somewhat different from each other so you can keep it fresh.
The only reason I can think of is that they want to stomp noobs? You can do it in other games too and be more impressive doing it because everyone is somewhat on equal ground unlike in extraction shooter.
It's the thrill of gambling your gear in the hopes of getting better gear in the future. You raise the stakes since the game starts and they get bigger and bigger as you run out of healing/bullets, or you get rare loot that you must survive in order to retain it. Since the win condition isn't killing but rather going to specific points of the map, theoretically you don't need shoot or heal or even die to win, you retain everything that you brought with you plus whatever you found.
It's this risk/reward gameplay loop that makes extraction shooters standout, though the game itself needs to be properly balanced in order to make the game fun, just like any pvp game.
There's probably a subset of pvp "sweats" that enjoy scrubstomping with (relatively) overpowered gear outside the reach of casuals and weekend warriors. You saw this a scant couple of times during D2 where some out of reach weapon dominated crucible lobbies with an entire slew of tryhards capitalizing on it, though more often it was a relatively common weapon being completely overtuned. Not saying that it's common, just that it exists.
Marathon gives off that impression because its balance is dogshit. If we take Escape from Tarkov as an example, there every player has weak spots where the hitbox can never be armored (legs,arms) or can armored up to a low level (neck,upper chest,stomach, face) so that even low level player or even a free kits can kill a sweat in one bullet if it hits the critical regions. The sweats do have an advantage, but there are mechanics that nullify those advantages, which Marathon currently does not have.
I disagree that extraction shooters appeal only to pub-stompers, there are better games for that, infact it's harder to pub-stomp in extraction shooters because of how they're balanced, well atleast in Tarkov and its clones. If you have a survival rate of around 50% or more in Tarkov, you probably are in the 1% of the playerbase.