How to not write bad - Ben Yagoda 2013

There is no reason ever to use boldface in a piece of writing, except for a section heading (like this)
How to not write wrong

Students commonly use bold instead of the proper typographical way to indicate emphasis or a title, which is italics. Aside from being counter to standard usage, it’s jarring; each boldfaced word makes the reader jump.

[Why do they insist on putting Hamlet in bold?]

Why do they insist on putting Hamlet in bold?