Thanks for that @paradigms.lost. You make a quite a few really good points in your response. The risks and downsides to specialisation mostly fall on the side of the specialised individuals rather than the producers themselves. This is probably why specialisation is still so strongly promoted.

There is also a difference in the type of specialisation. Specialisation in tasks that are repetitive and require very little cognitive thought process are likely to be boring, unsatisfying, and at risk of replacement by machine. This type of specialisation is also likely to be exploited in countries that have low-cost/slave labour.

There is also specialisation in jobs such as academia and science. Jobs that require skills that cannot be easily replicated by machines and are also mentally stimulating. These types of jobs benefit from specialisation. Even these jobs can cause isolation from the real world and create the problem of ivory tower syndrome. It can be easy to get too wrapped up in a particular area of specialisation and lose track of the bigger picture.