Yesterday, I was chatting with someone about the evolution of calculators and the importance of mental math. Growing up in India, no calculators were allowed K-12. Even undergrad colleges in India did not allow the use of calculators in classrooms. In comparison, when I came to college here in the US, calculators were common (outside of math classes).
Come to think of it, people have been using calculators for decades. The first portable calculator was launched in the 1970s. Before that, we used pebbles, bones, and an abacus at various points in history.
While basic calculators were widely used by businesses and academics, their adoption wasn't as widespread as the use of math in daily lives (which would require the use of mental math/calculator).
When the first mobile phones appeared on the market a lot of them came with a built-in basic calculator - addition, subtraction, multiplication, and division (and ability to handle decimals). Now, this gave calculators a new distribution channel. Phones were destined to be in every man's pocket. By using a mobile phone as a platform, the calculator was able to reach widespread distribution, far beyond what it achieved as a standalone device.
Like the example of the calculator shows, sometimes its easier to use an existing, widely distributed platform, to sell your product. For example, using Facebook or Instagram to sell your products instead of creating a standalone e-commerce app. This is because it is harder to get customers to download your app JUST so they can buy your product when they find something awesome, compared to asking them to open your page on an app like Instagram which they have already downloaded and use daily.
This strategy has its pros and cons. While its easier to acquire customers, cheaply, platform risk increases significantly. For example, if you are using Snapchat's platform, Evan Spiegel could decide to change some policies or terms of service and kick you off the platform in violation of the terms of service. Similarly, if you are on Facebook, and Zuckerberg greenlights a new feature which directly competes with your feature, FB can easily prioritise their service and ignore yours in their algorithmic feed.
As a result, I think existing platforms are extremely valuable for building a brand, acquiring early customers, proving the concept, and generating buzz and loyalty. But once you have a strong community, it is important to reduce platform risk but onboarding your customers to your own platform.