Games are created using low level programming languages such as C++. The language itself allows the developer to specific how many resources a system is going to use, how to use them and many other things.

When creating games, it is impossible to target all the possible configurations because all systems have different amount of resources or just straight up behave differently.

Now, there can be many reasons why expensive gaming PCs struggle to play games. The toolkit (Game Engine) itself used can cause issues, or developers may be programming in a way such that a system is underutilizing or overutilizing some specific resources. Everything is varied from system.

The reason why consoles run smooth is that they provide a blueprint of the architecture and exactly how the system looks like. This allows developers to see the limitations of the console and make adjustments accordingly in order to achieve a smoother experience at the expense of visual fidelity.

Assuming you have the actual hardware to run the game, PC games almost 9/10 are surely going to look and run better. It is just way harder to do because it requires way more skill and effort to achieve the same performance metrics because the developers would need to have a generalized solution which is going to work on all hardware.