Although Apple (AAPL) - Get Report has recently been taking steps to make its set-top box the best on the market, including the incorporation of a TV guide, Roku is still the king when it comes to streaming media players.

According to research from Parks Associates from this past May, Roku led all of its competitors in sales from first quarter 2015 to first quarter 2016, with its set-top boxes accounting for 30% of the marketplace. Amazon (AMZN) - Get Report and Alphabet (GOOGL) - Get Report tied for second with a 22% slice of the market each, and Apple TV claimed 20%.

Why has Roku, a small, privately-owned company that essentially manufactures a single product, done so well? It may be due to the unflashy nature of its product. The company prides itself on its box being "the simplest way to stream entertainment to your TV," and indeed, Roku has been widely praised by consumers as a streaming player that is easy-to-use.

Roku offers both a set-top box and a streaming stick, which serve the same media-streaming functions but differ in size and compatibility with Ethernet (boxes can connect to Ethernet, streaming sticks can only connect to Wi-Fi). Although you cannot watch live television on Roku, an increasing amount of consumers are cord-cutting anyways, as streaming content becomes increasingly popular.

Roku was founded in 2002 by Anthony Wood, who had previously launched the DVR brand ReplayTV (which was to be overshadowed by competitor TiVo). The company makes most of its revenue from selling set-top boxes and streaming sticks, although it also has revenue streams from Roku TVs (with the streaming media technology included in the product), from advertisements on its channels and from revenue-sharing with Roku's many content providers.

The company has yet to make an IPO, with Wood telling CNBC's "Squawk Alley" last January that he would not talk about plans to go public. If (or when) Roku does make an IPO, its stock price probably will not shoot up as high as competitors like Apple or Google, which are technology giants with a plethora of different revenue streams.

However, Roku's market dominance shows that a company does not need to be a conglomerate in order to achieve success. Roku is well set to remain a leader in the streaming media box market, perhaps because the company has been able to focus all of its attention on its main product. Indeed, sometimes less is more.