Kinda confused here, you said what I said was not true, and yes I agree with the rest of what you are saying.

You've specified in more detail than me how the feature works. I simply gave a summary of what it does.

When I mentioned 30fps, I meant that is the target. It is designed to free up more resources which makes a dramatic effect to very low-end systems and to those users, as /u/jusmar in this comment section has mentioned:

People who can't seem to close nonessential programs before playing games so they need their OS to soften the performance impact of their negligence.

Their game performance will improve, both minimum and average fps. For the majority of pc gamers out there who have gaming systems that exceed 30fps, will find game mode make an insignificant improvement and in fact, as many people with very high-end systems with higher threads on their cpu's, have found larger and more frequent frame drops with game mode enabled compared to disabled. This has already been tested, even LinusTechTips has tested this himself, thoroughly which proves higher end systems will suffer with game mode enabled, thus proving my original point.

Don't use game mode if you exceed 30fps in games, you will gain minimal improvement and if you have a high end system, some games will perform worse.