HTML was invented in 1980 and developed in 1990 for the sake of being able to share research papers. What do we use it for now? For just about everything, in other words, not what it was designed for.
LiveScript appeared in 1995 and was rebranded JavaScript in 1996 to try and ride on the popularity of Java's back even though it had nothing to do with Java. Support for it was horrific as well.
It was originally created as a toy language to glue things together on the web:
We aimed to provide a “glue language” for the Web designers and part time programmers who were building Web content from components such as images, plugins, and Java applets. We saw Java as the “component language” used by higher-priced programmers, where the glue programmers—the Web page designers—would assemble components and automate their interactions using [a scripting language].
What is it being used for today? Just about everything, in other words, no longer as just a glue language to validate fields and start Java applets and as a result, the legacy of it being a glue language sticks through the modern layers of ECMA6 and 7.
At the time, if you wanted a red link, you hardcoded that colour into the link. Only in 1996, CSS came along and support for it was horrifically bad, but it gave us the promise that we could now clean our HTML and remove all those inline colours and move the presentation to a separate file. CSS was also very minimal back then and very few browsers supported it.
CSS was pretty much designed around HTML which at the time if you wanted to layout a page nicely, you literally put a table tag on the page and stuffed some more table tags in the cells.
Since the web was designed with backwards compatibility in mind, all this legacy keeps on pulling along complicating things.
Broken? I'd say it was not originally designed for what we do with it today.