The tier list is a useful tool for ensuring maximum enjoyment of D&D. If you don't know about the tier list, then you unfortunately don't have access to a good and useful tool. If you know about the tier list and decide not to use it, you are ignoring a useful tool.

Whenever someone explains about tools to make a D&D game better, people always use the same arguments, "There's no one way to play D&D", "Are people who aren't doing this wrong", "If you're having fun you're doing it right". These are tired arguments used to avoid a topic rather than learn.

Fact, D&D is a complex game with lots to learn. Very few people have anything approaching a complete knowledge of D&D, and becoming knowledge of all the tricks and tools takes years. Fact, there are many tools, techniques, and pieces of knowledge you can use to make your game more enjoyable. If you are having fun without the tools, good for you. That doesn't mean you can't be having more fun with these tools, or that there won't be a situation where your enjoyment of the game will be compromised due to ignorance or a refusal to use these tools.

So the answer those questions, people who understand and use the tier system are in fact playing D&D more right than those who are not. By learning about a quirk of the D&D system, and using it to improve your game and solve potential issues before they start you can make your game better or more enjoyable. Learning more about the game won't make it worse, only better.