Steam marketplace reversal policy

I was reading a few incidents in the marketplace lately and it got me thinking of Steam Subscriber Agreement (https://store.steampowered.com/subscriber_agreement/?snr=1_44_44_)

I was not active in Steam back then, but from what I know steam has changed its policy over markeplace reversals. Meaning "all marketplace transactions are final", cannot be reversed or refunded etc etc etc..

But I was remembering 1 term in that agreement.. I found some time and searched for it.
It's actually 2 things:

a) 1.C. Your account
"When you complete Steam’s registration process, you create a Steam account ("Account"). Your Account may also include billing information you provide to Valve for the purchase of Subscriptions, Content and Services and any physical goods offered for purchase through Steam (“Hardware”). You may not reveal, share or otherwise allow others to use your password or Account except as otherwise specifically authorized by Valve. You are responsible for the confidentiality of your login and password and for the security of your computer system. Valve is not responsible for the use of your password and Account or for all of the communication and activity on Steam that results from use of your login name and password by you, or by any person to whom you may have intentionally or by negligence disclosed your login and/or password in violation of this confidentiality provision. Unless it results from Valve’s negligence or fault, Valve is not responsible for the use of your Account by a person who fraudulently used your login and password without your permission. If you believe that the confidentiality of your login and/or password may have been compromised, you must notify Valve via the support form (https://support.steampowered.com/newticket.php) without any delay."

I'm specifically referring to "Unless it results from Valve’s negligence or fault, Valve is not responsible for the use of your Account by a person who fraudulently used your login and password without your permission"

b) 4
"You may not use Cheats, automation software (bots), mods, hacks, or any other unauthorized third-party software, to modify or automate any Subscription Marketplace process or the process of Steam account creation."

What is something that would make Steam itself liable? What would be a case of steam negligence or fault?

Also, many times in such cases the "attacker" is using a scripted bot to run fast many transactions. If this is against their terms why is it not implemented in all hijacked accounts that did those transactions in this fashion?
Why there is no real-time delay on those transactions? A human hand cannot set 150 transactions in 10 minutes (random example.. Can be any number on any impossible time) etc.

"Valve is not responsible for the use of your Account by a person who fraudulently used your login and password without your permission."
There are cases where this doesn't happen from human error and it's impossible to find the source. I'm speaking of rare cases where Valve can't find any problem whatsoever on the data of the account but still recognizes it is not your use on your account (weird part here is there is no mention anywhere of how something like this is possible by Valve). It's a grey zone where Valve cannot "blame" the user but it's also not Valve's fault (sounds weird I know, but it has happened and no explanation was given as to how or why). In this scenario you get a connection to the 1.C. term which somehow voids the "all marketplace transactions are final". But.. How?.. I mean.. What can they see in theory for this to take effect?

I hope I'm making sense as to what I'm asking here. But to put it simply.. What would really make Valve to make that exception that is so vaguely written on their terms and reverse a marketplace transaction? Because it's certainly not out of the goodness of their hearts..

Also, in "Unless it results from Valve’s negligence or fault, Valve is not responsible for the use of your Account by a person who fraudulently used your login and password without your permission" it must have a hole.. If Valve is negligent then the next sentence is out the window