To be honest without luck, stuff like PvP would be boring. The whole reason why things like football, dark souls pvp, betting are so enjoyable and addictive is that uncertainty. If you know within seconds you are a better player than someone and it means they have no chance of winning would you enjoy that?
There is a fundamental flaw in that line of thinking, and that's that the person who is better on average is always the better person *this time*. The person who is better *this time* should win, but that isn't always the same person. That's why we play. You don't need luck for upsets.
By the way, what major outcome-altering factor exists in dark souls PvP that is luck-dependent? Damage is fixed based on equipment matchups and movesets/hits/timings are fixed also; I don't think anybody is going to make a case that lag is a good thing for the game and that's one of the few random factors known.
So in answer to your question- luck is benefiting both the skilled and unskilled players.
No, luck in this context harms both players and the game. By reducing the impact of possessing skill, you remove some of the incentive to attain skill, because skill matters less than it otherwise would. This is bad for both players, as it frustrates the skillful and removes encouragement of those lacking to improve. The game winds up with less depth and is dropped sooner in its life cycle.
Even if it reduces the skilled player's win ratio, the uncertainty it brings makes everything much more exciting as you don't know what will happen, even against a relatively less skilled opponent
Uncertainty does not require luck. If you're certain of the choices of your opponent, you need a better opponent, not to have him randomly deal triple damage to you.
The tricky bit it getting the balance right; how do you use randomness to introduce unpredictability without leveling the playing field (and effectively penalising good players)?
First you talk about luck, but then you ask a balance question. There is a reason for that. A desire for uncertainty is not a case for luck. It is a case for balance between choices such that it is possible to be unpredictable and still be effective.
If someone might do any of 2 things that can possibly work, vs 15 things that can possibly work, obviously the latter is going to be a deeper and more uncertain experience, and it will do so independently of the existence of any luck whatsoever.
Edit:
Since you mentioned football also, let me point out that madden
deliberately adds far more luck than exists in reality. In the NFL, defenders catch 70% of interceptions on average. In madden, that figure is less than 50%. In the NFL, an average halfback fumbles on right around 1% of carries (good ones less than half that). In madden, they fumble it several times more frequently.
Fumbles are luck-dependent factors in-game; poor throws resulting in opportunities for interceptions are almost independent from luck.
One turnover makes the difference in the outcome of a game a reasonable amount of the time; a differential of two has an enormous impact on who is likely to win.
Why, then, make ranked/competitive matches and even those played for money deliberately much more dependent on luck than the actual game?The best justification I'm seeing for it so far, and it is a pathetic one, is that it somehow makes games "more exciting". If rolling dice is exciting to you, fine. Go roll dice. Heck, go to Vegas and put money on rolling dice. Some people certainly find that exciting. But why do it in the framework of a game that would otherwise take skill? Why force people to play dice when they actually want to play Dark Souls or a different game? What message does penalizing skill send? What depth does it add to the game?