What i am saying is, and this has been proven time and time again, just because you have kills does not mean you have the win. So many people lose simply because someone split push to their nexus and people were so caught up in killing the 4 people again, for the 10th time, that the one person then is allowed to end the game. Even still, except for in low ranked games where there is a fairly big flux in game knowledge AND mechanics, there is much fewer kills in a game generally. For example, the worlds stuff that we were forced to watch for rewards (which i wanted, so i watched some).... the kills in the games were a bit higher than what i heard they normally were in the past, but not dramatically like everyone seems to make it out to seem.
Also, my point is that the two are very closely related, but you cant really have good mechanics unless you have good game knowledge. Wave management and knowing when to leave and when to not, are part of the same boat. The way i think of it, think of the game knowledge as formulating the plan, and mechanics being the plan put into action. You know that Velkoz has a knock up that requires a ball of energy to make it to the circle on the ground, so you as Yasuo wind wall and block it and avoid the ability. if you did not know what the velkoz had, you could not tell if you should wind wall or not, or if it even is able to be wind walled.
Mechanics increase your game knowledge, and game knowledge is required to have something to use mechanics with.
That being said, i am saying that i find both highly valuable, but that you can not have one without the other. You said yourself that game knowledge and strategy is drafting a team comp for example.... and then you said that league has more emphasis on who is able to kill and force the enemy out of lane. How do they do this? They pick a champion that they feel works well for the situation, or that they are comfortable with. Those that beat the people out of lane, generally have fought against that matchup before. Thus, bringing their game knowledge and strategy's from other games, they show better mechanics and win the lane and force the enemy out.
There is no way to separate the two things. There can be no emphasis taken on either side of it, because you can not have mechanics without game knowledge, and the only way to have game knowledge but no mechanics is watching someone else be playing while you are not playing at all and then you join in the game with all this game knowledge...... but absolutely no clue how to apply it or when to apply it. However, once they start playing, they get mechanics right away. They may be bad and sloppy, but they get better because of the game knowledge and knowing what to practice on first.... what champ they may want to get better at first... etc. Like if a new player actually took the advice to go to a custom game and last hit with no items to try to get around 100ish in 10 mins. They would apply the game knowledge on how to get mechanics and then they would have that mechanic. People view less things as strategy and more of "what you should be doing anyways"...
Strategy: a plan of action or policy designed to achieve a major or overall aim.
Killing the enemy adc, is in fact a strategy of Rengar's and Zeds for example. Then they kill whoever else. It is a plan, it is thought about, then it is put into action. They decide whether it is better to use their ulti to kill or not, if they should ignite or not, if they should flash for your death or not, etc. Usually this comes from hundreds of games with a certain champ to be very efficient with it. Further enforcing the fact that there can not be mechanics without game knowledge.
What you are refering to is more complex strategies, strategies that require multiple things going in a set way for the desired result, hopefully with steps that force the results to be the one desired.... which still work very well. For example the knock up comp of Malphite, Orianna, Wukong, Miss Fortune, and Yasuo for example... you see brute force, i see a well thought out plan that if executed could be very bad for the enemy team.