You have to think about how people respond to things. Social media in its current state has basically turned into a system that takes an event, removes all context, spins it in the most negative way imaginable, and then dogpiles on it to no end -- virtue signaling for imaginary points. There are often lots of things in government, and in life in general, where you must choose between two very negative choices. And the decision there does not necessarily imply that you're in any way satisfied with it, but you see it as the decision least likely to produce an awful outcome. Social media and this sort of logic are wholly and completely incompatible.

Take Khashoggi as a contemporary example. Undoubtedly there have been countless heavily classified conversations weighting the pros and cons of any action against Saudi Arabia or MBS as a result of this. How we are extremely dependent on Saudi Arabia for reasons outside the scope of this post, and they know this. And this is all happening at a time when Saudi:US relations souring would greatly stand to strengthen the geopolitical position and power of nations such as China and Russia. In my opinion it's extremely likely we will do nothing, but that's because it's better than doing something. If this was not classified, social media would throw a nonstop hissy fit. Not because they actually care or think we're making the wrong decision, but because it's an incredibly easy way score those imaginary points and followers which are the hottest commodity since sliced bread. Another issue here is that knowing the mechanisms of our decision making here, and how close we came to 'breaking', would be incredibly valuable information to nations such as Saudi Arabia which they could then use to exploit the US.

So while I do agree with you that classification is very often abused, I also think there are indeed vast amounts of information that must be classified. People are not mature enough to impartially process our decision making processes, and the details of such processes would provide invaluable information to other nations which could then be used to exploit the US.