I have a confession: I have a personal vendetta against the word 'which' and a loving addiction to the word 'that'. I can't stand the former, and I always cringe when I'm told I have too many of the latter-- because it means I'll inevitably have to switch one for the other. Just thinking about it makes me feel like a little kid, who secretly wishes she could eat candy for every meal, and while struggling to finish her vegetables.
- eradicating words like was, were, that, just, and adverbs
- getting rid of prologues
- staying in one character's head per scene, rather than head-hopping
- reducing unnecessary prepositional phrases
- streamlining unnecessary words to cut out general wordiness
These become conventions of modern literature for a good reason-- typically they help to smooth flow, in turn making a work easier and more accessible for the reader. I'm not knocking them even slightly, and often the overuse of our blacklisted words (was/were/that/just/adverbs/etc) is a sign of a writer who still has some growing to do. Another sign is taking conventional wisdom and turning it into a zero-tolerance policy.
We can compare this to dieting, where words like adverbs and passive verbs can be likened to fats and sugars. A few are okay-- healthy even. But going overboard with them can make prose bloated and blubbery. On the other end of the spectrum, we've all seen those diets that try to utterly eliminate a certain type of food from your life. Often enough such diets fail because they're so awkward and difficult to manage (one reason why I have a lot of respect for vegans and those with food allergies). In the same way, trying to completely eradicate certain words can make prose clunky and awkward.
Sometimes the best way to write a sentence is to use passive tense or an adverb. Sometimes bending over backwards to avoid using a word makes writing awkward. And sometimes conventional wisdom will change.
Like sugars and fats in a healthy diet, sometimes the best way to go is to cut down without cutting out. In the end, everyone has to find the right balance for their own writing style.
My personal standard regarding 'was/were's and adverbs is an average of about one or two per page-- just enough to make the flow as smooth as chocolate.