Breaking down silos de-risks a company, despite some of the costs you mentioned. Especially after covid, companies capitalize on the flexibility of employees and lack of (physical) offices. Employees can be replaced like never before.
But even without that in mind, breaking silos can also put the right people in the loop - for every successful silo you mentioned, I bet there is a successful company which was able to have a good mix of people from different teams.
For me it always boils down to: what does the company want? Who they want to be in the next 3-5-10 years? Based on this you need to have proper management training. Without that, they simply throw engineers at the problem, which as you mentioned, can backfire. If you as an organization are able to scale well (even with some small and monitored silos) I don't see why it should be a problem.
Reality is: companies want to be able to scale like Google for their pet projects, fire fast upon need, have a lot of teams all with the performance of 10x engineers, etc etc. That's the BS they write on their about page.
Do they have agile coaches? Do they have people that help them organize work? Skilled people, not random guy that developed software all his life and now he/she wants to try something new, and he/she read a book over the weekend or listened to some podcasts..
People have high expectations by paying little. It takes effort to do things right. That's in my opinion the truth.