This conflates two kinds of slowdowns. Post-implementation stuff like thorough peer reviews and automated testing followed by manual QA is usually a net gain on a long enough timeline. The damning and soul-draining part is pre-implementation -- how many people need to agree that the line of code will be changed and how many people must opine on the change before it can be shot over the Dev | QA wall.

The worst place I ever worked at had mandatory "ticket refinement" - a feature or a bug couldn't be worked on until it had been through a "refinement session", in which everyone had to chime in, and the ticket wasn't considered refined until everyone on the team fully agreed with the implementation. Naturally over time, this devolved first into writing pseudo-code in Jira tickets and then into near-production code in a google doc overflowing with comments. Leaving that company I told my manager "this is a team of 4 'senior' engineers, I'd suggest you get one proper senior engineer and 3 typists". Nowadays, you could probably shove minutes from those meetings into copilot and call it a day.

Of course, the flipside of this was that comp was about on par with the market, and the perks were top-tier. If you're okay with doing the bare minimum while spending ~20-30 hours a week on total nonsense, it's probably the dream job.