For context, we're defining strategy in this sense.
-Strategy is your plan of attack (via macro and micro) to win the game (aka your win condition).
-Strategy can be employed by your enemy as well as your teammates. Everyone is going to have their own win conditions they want to play to, and part of strategy is knowing who you want to work with. Strategy is about when and where to compromise and where you should abandon a strategy altogether (i.e. stop trying to be a carry and play anti-carry for a stronger carry on the opposing team).
-Strategy should be flexible, as an inflexible strategy is a surefire way to lose.
Now let's use a little psychology. Most people want to be the carry. Their win condition will often be, "I want to have the greatest impact on the game." because let's be real. You want to feel like you're good at the game. Nothing wrong with that. I want you to try your hardest in games, especially if you're on my team. The big difference is that some people see damage as the greatest impact, some see ward coverage, roaming and macro, some see lockup.
The problem is that most people get stuck on the first definition and cannot or do not process anything else. Also, due to perceptions of a high damage meta, people think that the best way to have that impact is to do the most damage. And you can see this in peoples' attitudes and perceptions about the current state of matches they're in.
Let's use Zed for example. You're playing against Zed and you have a lapse in judgment and he and his jungler kill you. You get frustrated because Zed has an insane amount of damage, and that's understandable, but what you fail to consider is that he and his jungler are employing strategy, and they knew you didn't have a brush warded so they used that to kill you. Maybe you get upset with your jungler, and that's another problem because ~~junglers are bad and I hate junglers~~ maybe the jungler has a different strategy from the one you had. Also, your strategy is inflexible because you're hoping that he'll match you 1 for 1 with the ganks that the enemy jungler performs, and that's simply unrealistic. Assuming you are right and the jungler should've counterganked, you still run into the problem that you're expecting another person to know the exact same things you know, and vice versa when he flames you.
Maybe you've got a bad teammate, and that's annoying in and of itself because people are extraordinarily inconsistent, but expecting everyone to perform to the standards you have of players in the role again is inflexible. Expecting people to play up to par every game means you leave yourself open because you don't feel the need to perform in that category. i.e. maybe you don't feel the need to buy more armor because your adc shouldn't feed in this lane. You don't buy armor and the 5/0 Lucian melts you.
The reason this becomes so difficult is because the choices you make will usually end up shafting a teammate. If you gank top, you leave bot exposed to getting ganked. If you go to help the jungler that's getting invaded, you risk setting yourself behind. Sometimes, it will end up feeling like you hurt yourself to help a useless teammate, or that a teammate is taking advantage of you to get to their win condition. These calls won't always work out and they can even lose you games.
And that gets us to the main point of this post. Many people see, "oh my teammate doesn't want to help me reach my win condition so they're selfish" or, "they're 2/0 and do more damage than me. I can't fight them. Game's over." and instead of changing their strategy to focus on another possible winning outcome, their mental shatters and they give up. It's frustrating. Some games are just lost and everyone gets outplayed and that's fine, but I've played countless games where one person is horribly behind and instead of relying on the guy who is ridiculously ahead and playing for them, they give up entirely. A good example of what I'm saying is that one guy playing Tryndamere who will feed 0/4 in the laning phase and will continue to afk soft int because he's not as strong as the other top laner but he says he can not play with the team under any circumstance (I know everyone here has had that happen at least once in their games, it's basically a League initiation ritual at this point).
The number of people doing that recently feels like it has gone up dramatically, and it leads to an unsatisfying and unenjoyable game experience. You see it when the midlaner dies over and over to LB but hasn't bought any MR or health or taken it in their runes. When one gank goes sour and someone calls for open mid, or the jungler doesn't come to your lane so you buy 3 tears. Personally, in my last 4 promos I've had at least one game where a teammate was so uncooperative that we simply couldn't win because they were too stubborn to change their strategy to better reflect the state of the game.
So anyway, despite the high damage meta, I still do think the game requires a good deal of strategy. It's just that people are simply unwilling to adapt.
P.S. yes that includes changing your champion picks. I don't think one champion should be all you need to play a role and I certainly don't think anyone should limit themselves to one single role, because both reduce your perspective of the game.