Even if it was only 2 more top end with ToV, ambush multiplier makes it into 8ish (ambush w/ dagger is somewhere around 400% wpn dmg + initial). If you happen to crit, this 8 extra damage gets multiplied by 2 (or 200%) so it is now 16 more damage. If efc happens to have 10 stacks, it gets multiplied by yet another 200%. Now we're talking about 32 extra damage already. While this is not huge and obv gets a little smaller by reduction from resil and armor, it is still noticeable and can and will make a change at your offensive capabilities at some point.
Now Mocha, you are talking about a whole another topic here. Everyone knows that how you use your abilities, how well you can sync and interact DOES make a bigger difference to the outcome of offence / whole game than how you choose to equip your twink. But gearing makes a difference to it aswell, you can't deny it. However Marginal the difference between "best" and "second best", at some point it IS going to make or break the game. No matter if you play at skillcap, at an average level or way under it.
Even if you did everything near perfect, there's a chance of RNG uppercutting you right in the nutsack. You land your kick and sap perfectly, do everything you can in good order and efc gets to 20hp before your whole O gets cc'd for enought time for def to heal FC to full. He doesn't come close to death after that and game ends 1-0 to your loss. There's a ton of things you could blame why efc didnt quite drop. Teammates, latency, efc or def being so strong or whatever. Perhaps you don't blame anything, just think "well, shit" and move on to the next game. But if you weren't in the most optimal gear in the situation where everything went perfect but efc didn't die because of 5 or 20hp, you couldn't possibly say "Well, it didnt make a difference if I had used a better weapon".
And bringing your race choise to this discussion is completely irrelevant, AFAIK, they benefit from ToV and Kris exactly