I think Dreamweaver being pushed about as a leading web development tool is harmful. It's actually very bad for what needs to be done and almost always contributes to bad code. The best IDE for frontend web development should be a text editor with syntax highlighting, block-start/end matching and a few hotkeys to speed up the writing of HTML (ZEN Coding anyone?). The design view is very harmful and the code editor is not much better. No matter where ever you untick "Use tabs" or similar, Dreamweaver will still use tabs. It really ruins code.
Another thing is many web developers will use meaningless class/id names and fall back to generic terms such as "floatLeft", which is pretty bad.
Although there is SASS, this isn't often available in a lot of projects so you do often have to repeat yourself a lot in CSS... unless you resort to the above. Which is worse? That's left as an exercise.
Then there's people who still use HTML that went stale over ten years ago just to do a quick job. Yeah, you save time by writing by a) writing less characters and b) not having to define any potential CSS rules but then it loses all meaning. That is, unless, you give it meaning which then makes it redundant since a better alternative could have been used.
Another thing is how you're forced to use a lot of divs to come up with a good pure HTML/CSS solution to something. Although there is now HTML5, it's obviously not supported by the older browsers which a good percentage of the Internet still uses.
Rant over.