And why do we not anymore make use of it, but instead implemented separate JSON loading functionality in JavaScript? Can you think of any reasons beyond performance?

I'd be surprised if there is a performance benefit of processing json with eval(). Browsers optimize the heck out of JSON.

You are arguing against the opposite of what the comment you answered to said.

Why did you opt in for such a comment while a straight forward response without belittling tone would have achieved the same?

I actually gave it some thought. I had written the actual reason first, but I realized that the person I was responding to must know this, yet keeps arguing in that eval is just fine.

I would say they are arguing that in bad faith, so I wanted to enter a dialogue where they are either forced to agree, or more likely, not respond at all.