"JS is his baby that’s all there needs to be said about the person’s motivations."

"During these formative years of the Web, web pages could only be static, lacking the capability for dynamic behavior after the page was loaded in the browser. There was a desire in the flourishing web development scene to remove this limitation, so in 1995, Netscape decided to add a scripting language to Navigator. They pursued two routes to achieve this: collaborating with Sun Microsystems to embed the Java programming language, while also hiring Brendan Eich to embed the Scheme language."

https://en.wikipedia.org/wiki/JavaScript

I think you're confusing the reasons behind the initial intent of JS versus what it has evolved into almost 30 years later.