I'd say it's less a matter of ignorance, and more a matter of "you probably should get your eyes checked". It's always been right there in the top-left corner, a little under the site logo.
There is an option when searching the forums and their sub-sections.
"Filter results by forum"
and
"and/or by user"
That's exactly what you're looking for. You're just too lazy to use it and want a forum search for every section when it's totally uncalled for.
Hope this answered your question/request.