Sherlock: 6 Reasons It Needs To End (And 4 Reasons It Should Come Back)

2. It's Run Out of Major Material To Adapt

As you may well know, Sherlock was born out of Moffat and Gatiss' life-long love of the Sherlock Holmes stories of Arthur Conan Doyle. As such, their show is stuffed to the rafters with callbacks to those novels. In fact, most of the character moments or plot points that they have been praised for are actually just extrapolated from Doyle's work.

So far on the show, for example, we have seen Sherlock meet the one woman who turns his head (Irene Adler), encounter several of Doyle's finest villains, and face the iconic showdown between him and Moriarty (in about three different variations).

In fact, the show has burnt through so many of the major moments from the canon that season four carved out its own path - inventing Sherlock's secret sister and John's baby daughter. Some of these ideas might have featured in prior Holmes adaptations but they are not from Doyle's original stories.

Sherlock has relied so heavily on the work of Doyle, using it as a rough guideline for the development of the show, that it's difficult to imagine it continuing without that.