[_micheee]

I just found out you may - even in current HTML use entity references in attribute values, it’s just you don’t have to anymore, when the ampersand is not ambiguous.

The spec states it as: “Attribute values are a mixture of text and character references, except with the additional restriction that the text cannot contain an ambiguous ampersand.”

Whereas in the the days before HTML5 this has been mandatory.

> HTML 4.01 Specification – Appendix B.2.2 “Ampersands in URI attribute values”

https://www.w3.org/TR/html401/appendix/notes.html#h-B.2.2

> Unfortunately, the use of the “&” character to separate form fields interacts with its use in SGML attribute values to delimit character entity references.

[someonebaggy]

That's the same as main body text isn't it? And you have to be able to use them so you can escape " just like you have to escape < in main text.

HTML5 standardized how to interpret formerly invalid documents because it was more important to be consistent than to be correct.