If it only was so simple... no matter what, it costs companies such as Dropbox a lot a lot of extra effort to appease all possible companies that can file complaints. That could cause them to go out of business, to have to charge more money, and/or be really restrictive to what files and users they allow.
A net loss for all users of the internet, especially law-abiding ones.
It does. The technical implementation can have a lot of effect on the chilling effect of a law.
Let's take the extremes. If the technical implementation is "we'll send a drone to fire a missile at your building", people will be much more scared to take any risk at all of hosting user-generated content than if the implementation is "you'll get a warning and a $5 fine".
Everything considered, "We'll arrest you and everyone that works for your company and nuke your DNS entry" is pretty chilling. If they only punished bank misconduct that hard...
A net loss for all users of the internet, especially law-abiding ones.