The PMs that take all the credit are bad PMs. The best PMs I've worked with do a ton of behind-the-scenes work and give all the credit to the team. Having a PM that takes care of...
> analytics, user feedback, market trends, business concerns, etc.
..will boost productivity for any engineer or designer.
Oftentimes those people trying to portray a 'Slick' exterior are doing so due to the need to portray a sense of success/confidence for their team, to make sure they retain their existing budget and that the team doesn't get moved to other projects or terminated entirely.
It's horrendously inefficient for an organization to take away Product Managers. If you want to bring every designer and every developer and ever sales person... and basically your whole company to a meeting to make a decision... maybe you'll get away with cutting the Product Manager role... But there's so much inherent compromise and horse trading as part of every product launch / sprint.
Without someone to organize all that, you're going to waste a lot of time and force a lot of highly skilled people to do things that aren't in their wheelhouse. And then... at the end of the day... who is on the hook for strategy? "Oh, hey we built the wrong MVP so I guess we'll sack some of our <rolls the dice...> Visual Designers!" That makes no sense.
Any complex system or organization will need a management layer... think of them as lubrication if you want... to help all the different parts move efficiently. The team is responsible for the success of the endeavor, anyone worth keeping in an organization knows how to give praise where it's due... if you have individuals trying to take credit for teamwork... that's an issue you should take up with HR.
As a company scales, there is a tendency to embrace specializations through a division of labor. Of course, different companies adopt different models for various reasons. e.g. Do you need dedicated QA or does that fall upon the developers? With these decisions come trade-offs because you can't optimize for everything. Your proposed model can work, but is far less common in large tech companies because of the overhead of coordinating/communicating across lots of people which tends to fall upon PMs.