Not to pick on you specifically, but this view is way too wrong to be so common.
The information economy is fundamentally different from the industrial economy for (at least) two reasons:
- Extremely high capital intensity
- Positive reinforcement through network effects (same and cross-side)
As a result, market concentration in information and technology markets is extremely high compared with other industries. It's not a conspiracy, and it's not something anyone can change. It's just the nature of the product itself.
There are a few strategies to combat it (open source, adversarial interop, etc...) but "just build your own" isn't one of them. Because it's almost always impossible in practice.