I have some experience with work councils in Germany and they have some significant downsides, including for employees, that we need to be honest about. Yes, employees get credible representation at the most senior levels of management, but that comes at a cost. My experience may not be universal but from what I gather it is representative.
First, works councils are strongly biased toward the organizational status quo by default. They can deny/delay opportunities to individual employees against the wishes of that employee and even though the works council has no credible claim to skin in the game. I've seen it happen and it demotivates employees it happens to. Companies use a lot of hacks to informally let people reorganize themselves without the consent of the works council to get around this.
Second, many trivial and inconsequential operational decisions become glacially slow because works councils tend to micromanage all of them at ponderous speed. Even obvious employee issues which would be resolved in 30 seconds at an American company can take months when the works council is involved, all to the benefit of no one really. This takes a very visible toll on speed of execution. It creates interesting dynamics when the company is global because the rest of the company may not be able to wait for the works council, so the employees under the works council may feel like they are on the outside looking in as the rest of the company moves forward.
The loss of autonomy over my own career would bother me as an employee. The loss of operational agility and execution speed would bother me as a business.
Sounds like your company wasn't familiar with how to handle a works council and treated it as an annoying necessary evil. AFAIU works councils are not supposed to be handled like that. They are supposed to be an integrated part of management, so them blocking something after a decision has been made just won't happen. If you do it that way, they won't like you.
The usually decent working relationship between management and works council is part of unions not being seen as petty (e.g. "employee X is strictly forbidden to do work Y even for a second, consequences be damned") and greedy here in Germany. Wal-Mart tried union busting here and it didn't go well at all.
All that being said, a well handled works council is probably going to slow down a company, but not after decisions have been made as you described. It is also going to help make better decisions sometimes.
This was at a large, established German company with German management. It wasn't as extreme as you are reading it but these dynamics did exist. Having large American offices working closely with the German ones made the impact of the works council on the operation of the company quite obvious because the Americans on a team were not subject to it (and there was a directive to operate "west coast style"). My other American friends that worked many years for German companies observed the same patterns.
I'm not saying works councils are bad per se, but they do have an effect on flexibility and execution speed that is significant enough that many Americans notice, especially in the western US where fast and flexible is the native mode of business (eastern US traditionally has a bit more rigid and European-like business culture).
https://en.wikipedia.org/wiki/Works_council