Release engineering is a conservative profession. They won't thank you for upsetting all their established processes, introducing new software and systems that

Release engineering is a conservative profession. They won't thank you for upsetting all their established processes, introducing new software and systems that have to be maintained, and kept running just because you don't like how your code is laid out. It's harder to make a business value case for this type of change - there are only vaguely worded promises of "improved developer velocity". Contrast that with a change that automates or makes faster some aspect of building and releasing - a professional release engineering team would be all over it because they can demonstrate value in that work. In any company beyond 50 people, there are multiple engineering managers, directors or the VP of engineering that will need to back this initiative to make the release engineering team do it. It's really not as simple as "dump all the code in one repo". I'm speaking from experience.