Not really all that suprising.
When major leadership keeps leaving[1] it feels like it's more of an ego, expectations, and political problem than a technical one.
[0]: https://mondaynote.com/teslas-new-car-smell-315c72c955d3
[1]: https://www.bloomberg.com/news/articles/2016-05-04/two-tesla...
Also I agree with you that it feels that they belive that they can do everything better than anybody else and thus try to do everything themselves.