Interesting question. Let's put it this way: the advantage is decision made by only one person, the disadvantage is decisions made by only that person. Why is it kept the way it is until now? It's probably because the advantage outweights the disadvanatge, but how? I think it comes down to the decision maker himself. There are qualities required to be such person, and I think those quality partially eliminiate the disadvantages we are afraid of: the person has to be trustworthy enough, knows enough about the project/company and be respected and trusted by many others. I think the process of choosing such person itself has already helped with limiting the disadvantage.  

I think one person having decision making powers can be a bonus when kept to specific, time-limited scenarios. When the person making decisions has lots of experience and a clear idea of what needs to be accomplished, the freedom to get things done can be a benefit. This works best for single projects in short sprints. When one person becomes responsible for multiple projects they may lose focus and ability to stay up to date on all the information necessary to make decisions, turning what was an advantage(one person controlling decisions) into a disadvantageous bottleneck.

To make single person decision making work better, setting up a "predecision consultation" process can help. This means the decision maker holds short meetings with key team members to gather different ideas and expertise. After making the final decision, they should explain it clearly, showing how the team's input was used. Adding a "lessons learned" process after big decisions can highlight what worked well and what did not, building trust and accountability. This way, the organization keeps the speed of one person decision making while improving decisions with input from the whole team.

I think a solution to this problem could be creating surveys on staff satisfaction with the managers, as well as creating meetings to discuss and align team values and goals. When the manager hears out the opinions from the staff, they can use that to make better decisions that more closely aligns with everyone ideas. Showing that the manager wants to hear out everyone's opinion and beliefs show that they are flexible, helps prevent disappointment from their staff, and improves chances of project success.