Because they make the rules, and they like to have their own office. Life isn't fair.

Correct answer, but one corollary: If the only reason you have an office in an open office setting is because you make the rules, you're not a leader. You're a "boss".

Confidential discussions: hirings, firings, compensation talks, bonus talks, need-to-know and leadership-only conversations, etc.

They could use a conference room for such things.

Then they perma-book the conference room and use it as a de facto office.

Maybe at that point they shouldn't be using an open office layout.

In some case where leaders are GIVEN their own offices, they are trusted to have one in exchange for their capability in making important decision which requires low level of noise, and holding confidential meeting which requires privacy.

Open office is notorious for the noise and distractions.

They talk a lot. Honestly I am happy that they are given offices while I work in peace.

The "peace" of the open office layout?

I have worked in places where leaders shared the open space, to be honest the was strange since they (as do HR or Finance) have confidential material as part of their day to day work.

If employees are expected to work with Chromebooks why are developers given Macbooks/Thinkpads/more powerful laptops?

They’ll usually have both. The office is supposed to be where you discuss things that shouldn’t be overheard. And to slack.

Because of the open space. Observations are wider