How important is a good mouse and keyboard in gaming?

The Razer Huntsman Mini and Razer Viper V2 Pro (Image via Razer)
The keyboard and mouse are the primary input devices of a PC and make a big difference in making or breaking the gaming experience. When PC gaming becomes a hobby, getting the best component for every setup aspect turns from a want to a need. Gaming mice and keyboards must be comfortable, accurate, and long-lasting while adding some personality to the setup. But how important are they in adding to a user's gaming performance? Upgrading to gaming mouse and keyboard should not be top priority [embed]https://www.youtube.com/watch?v=GBYHBy6mQcA[/embed] Most manufacturers add the term "gaming" to their products to cater to a broader audience, even if the quality is not up to the mark. There are thousands of keyboards and mice on the market that are unsuitable for gaming but can still be used by casual gamers...