A world where perception has no relation to reality is one where your self improvement post has no truth or purpose what so ever.

While I agree that the perception statement may be written too absolutely, I agree with the statement to a degree.

As an example, if 5 people see an accident, there are likely to be 5 different accounts of the event. If perception and reality were correlated 100%, then there would either have to be 5 different realities or the accounts would have to match 100% every single time.

What people perceive can become their reality as they see it, but it's not necessarily objective reality as others see it.

have fun living in a world of inexplicable valueless nothing where you have no agency over your own mind.

Here you're creating an absolute where one may not have existed in the earlier piece. Being able to watch one's thoughts doesn't mean that people have NO control over their thoughts. But it also doesn't mean they have 100% control over their thoughts.

Here's an experiment if you feel you have 100% control over your thoughts.

Don't think of this video ever again. Mana mana. You might not even need to click on it. But if you do, mana mana, definitely don't think of this video ever again.

Also, if you have total control over your thoughts, you'd be able to eliminate any negative thoughts, worries or thoughts that bring any emotional pain since that wouldn't be very useful.

I'd be dubious if you claimed you had complete control over your thoughts. Even Jesus and Buddha didn't claim that.