By selecting an inflexible platform as the basis of your business, you will need to invest heavily in development or adopt your business model, forcing a re-build of your solution every time your business direction changes.
There is a high risk of spending a lot of time and effort on delivering functionalities that are not valuable to customers, and therefore does not provide traction. Even if it is possible to create your desired functionality at the end of the project, it will demand significant additional time and money.
Traditional licensing is also a challenge for startups. For example, when building your own industry or market-specific platform to resell, you are usually limited not just by the technical weaknesses of “native” e-commerce solutions, but also by their licensing policies, which make it impossible for startups to earn money.
The lack of experience in selecting e-commerce solutions can be a killer for startups due to the reasons listed. Facing these challenges, startups often decide to build a unique in-house solution because it looks deceptfully cheap.
Building an in-house solution often entails the same issues as choosing an inflexible platform (too long, expensive) along with additional overheads, such as the risk of dependency on internal technical specialists. Imagine only a few people in the world know how to maintain your solution - it's a risky proposition.