Why is the source code only for text?

Question

All my life I have used text editors for source code. I can’t believe that we are all doing this! There must be a better way.

I don’t mean that I want to use the WYSIWYG editor, I usually hate those because they definitely don’t give what you want.

No, I mean the text editor of the source code, which is greatly improved by the following additional ones:

include images, excel data, pdf, etc. INSIDE the source code, to explain certain data structures, include (layout) screenshots of what the client wants, etc. Of course, with the ability to minify / hide / fold these things. (the advantage of this, unlike a separate file, is understandable, you want to save this information along with your source code)
comments are not like text, but more like post-like elements, resizable, movable, interactive, etc.
Class definitions and instances are not as text, but as interactive box objects, possibly even with an icon, to quickly see in the source code the class of which is an object).
which are now 2 characters in the form of 1 character. For example: → in PHP as a real arrow.
The ability to use colors, different text sizes, and other layout tools inside the source code (I'm not talking about automatic syntax coloring, it is sometimes useful to highlight specific blocks of text using layout tools like you do in Word)
, / , 1 ( Adobe Illustrator, , ).