I can believe that. My father often bugs me to buy things he saw advertised on Facebook ads. For older generation like him who spend a lot of time on Facebook, Facebook is a good avenue for non-Amazon sites to peddle their wares.
On one hand, it's worrying that Amazon is so huge that we have these two categories; on the other hand we should be glad that there still is some "non-Amazon" left...
This assumes it's in Amazon's interest for there not to be.
Theoretically all companies under capitalism would want to become true monopolies because having competition means leaving money on the table, but in practice a duopoly or a de facto monopoly is preferable to skirt regulations and interventions. There is a good reason Google still props up Mozilla despite competing with them in the browser space.
It would also be interesting so see how many of the larger non-Amazons run on AWS.
If Amazon ever tries to get into Switzerland again we are getting the pitchforks out.
It's so nice to have hundreds of small online shops actually competing with quality and or cheap products. Instead of a AliExpress clone with worse support.