Perhaps a web-to-pdf or htm capture/edit/annotate tool, or the ability to keep whatever parts of the page we want & delete the rest is asking a lot, but I know I would get a lot of use out of it.

Web to pdf seems almost commonplace, nowadays. Many apps & browser extensions for this are available, but I prefer to keep my related information in DoogiePIM, where I have the most functional options available for my needs.

I'll try pasting or exporting from one of these apps into documents & see what happens.