Keith, As a LAMP developer using Linux I am in the same boat. My tool set is Gimp for images, I don't edit video myself but have it prepared per the site specs by others. As far as editors, I moved away from WYSIWYG editors in favor of Sublime Text for simple stuff and PHPStorm (not FOSS) for my full IDE. Netbeans is the closet thing to PHPStorm that I have used. I've tried Geany, Gedit, Bluefish, Netbeans, Eclipse, Komodo Edit and IDE, and prefer to spend the $99 for the PHPStorm License. It is java based and works on all platforms.
With web development moving to mobile first responsive design, web sites are moving away from simple CSS and implementing SCSS/SASS, more Javascript (jQuery frontend, NODE.js backend), and version control (VCS) like Git. You quickly realize that editors like Dreamweaver just don't have the breadth of built-in tools to help with your workflow.
Browser developer tools such as Firebug by Mozilla, and Chorme's Developer Tools offer more inspection tools than Dreamweaver (or Bluefish) along with built in debuggers for JavaScript that let you set breakpoints, step in, through, and out of js functions to inspect variables, array key value pairs etc. Both of these browsers will even reference the SCSS file that generated the CSS. As far as IE load Windows with IE in a VM and test it there or get an account with a multi-browser testing site in the cloud.
Maybe some of these other WYSIWYG editors may be fine for smaller projects (I still prefer Sublime Text for this). But for the enterprise sites (CMS-based 150k plus lines of code) I work on I need an IDE that can catalogue Ruby, JavaScript, SCSS, PHP, and SQL at a minimum. And a good IDE can inspect, create, and edit your SQL databases, transpile SCSS on the fly, bring up your LAMP server (Vagrant), and manage your VCS. Netbeans (IMHO) is the full FOSS IDE that is the easiest to install and configure and use out of the box.
Hope this perspective helps.