Some games seem overly addicted to RNG.
It's been one of the hottest topics for the entirety of Path of Exile's existence, for example. It's not that there's any specific chance or that someone is experiencing too much of a singular mechanic, it's that there's simply too much RNG, and that the RNG is overly negative. The phrase for Path of Exile is "RNG on RNG on RNG on RNG".
It's the difference between playing a chance effected game (RISK, the board game) and a chance heavy game (Tournament No-Limit Texas Hold'em Poker). A very experienced RISK player, when faced with a table of incompetant newbs, will never lose, even though they might suffer awful luck in the game. A very experienced N-LTH'em player could face a table of incompetant newbs and fall foul to game-ending luck.
In a basic D&D game you have Chance-to-Hit RNG then, if successful, an RNG total of the damage. So you have two RNGs, but only one is purely negative, the other will always provide *something* positive.
By adding another RNG before the Chance-to-Hit, a Chance-to-Fire, you're not only adding a third RNG but you're also adding a second purely negative RNG.
So you have:
1. Catastrophic fail or small hit
2. Catastrophic fail or small hit
3. Small hit varied by degrees of smallness
It doesn't actually matter what that new RNG is that you've added, it doesn't matter what name you give it - you could have a 'butter fingers' RNG instead where the character drops their gun. But in this game the new RNG is called 'Jam'. Sorry player, we're making your experience more 'potentially negative' because we believe that's what makes RNG fun and what makes games 'better'...
If you're looking for practical solutions rather than just pissant negativity (oh the irony) then you have to approach the topic from a whole new perspective that you are likely incapable of - because you'd already be obviously aware of it if you were capable of understanding it.
Another way to 'solve' the 'fun' of RNG on RNG on RNG on RNG is to, for example:
1. Catastrophic Fail (percentage improvable by 'various' methods) or small hit
2. Hit for small damage or (percentage chance improvable by 'various' methods) chance of Arterial Strike
3. Arterial Strike (if attained) varied by degrees of smallness
However, you could also just ditch as much RNG as possible and have a basic:
1. Catastrophic fail or small, unvariable hit
RPGs offer so many other opportunities for RNG fun, there's actually little reason to have so much of it involved in the combat beyond the basics. With Path of Exile, for example, ALL of their RNG on RNG on RNG on RNG issues are entirely non-combat related. I don't believe anyone's ever shown much thread'age about actual combat RNG beyond the absolute basic nerf/buff level of melee or ranged 'Chance-to-Hit'.
Yes, you want lots of RNG because micromanagers love all the what-effects-what-decision in RPGs, but you can effect combat RNG with so many non-wholly-negative things I could list examples for 100s more lines of post...
TL:DR - it's not the word or effect 'jam' that people are criticising, it's the unnecessary extra layer of purely negative RNG which is, quite obviously, producing too great a negative emotion for what it is worth in the game's whole. ie: There's so much good stuff, why is it making me focus on this really rather tiny 'irritating' part so much. Find something more 'attractive' to 'balance' a battle with...