Because their use is not sustainable because their formation takes billions of years to renew them
There's a great picture that I attached below that is a great representation
Founder effect or population bottleneck refer to events which bring about reduction in the genetic variability of a particular specie population. Such events typically drastically reduce the gene pool of the population and produce a smaller number of population with less genetic diversity. An example of a population bottleneck is a genocide event. Such event will destroy a large percentage of the affected population leaving only a smaller population with less genetic diversity. i hope these helps.
The term “carpetbaggers” refers to Northerners who moved to the South after the Civil War, during Reconstruction. Many carpetbaggers were said to have moved South for their own financial and political gains. Scalawags were white Southerners who cooperated politically with black freedmen and Northern newcomers.
hope this helped :)