I worked for a client where we had successfully delivered a working FOH site and booking/order system. A new head of marketing joined, and from the first meeting this guy proclaimed himself as a "tech lead" and evangelist. He wanted "full FTP access" within the first 5 minutes of our meeting. We told him we didn't use FTP as everything was deployed via our CI pipeline, and he kicked off.
After some crisis meetings, he said he wanted to change the entire CMS to be HTML boxes, threatening to ditch us if we didn't give him what we wanted. They were paying lots for this change, so in the end we obliged. He proceeded to delete basically everything we'd built, and tried to replicate all functionality using a A/B injection tool and a HTML field. Clients were pissed, because none of it worked, and they lost some serious money from it.
In the end, we rolled back and said "fuck it, full git access, you're a dev now", and at midnight he brought the site down because he decided to rewrite some db transaction logic to write data to another store. To him, transactions were "outdated tech", and he tried to clean it up by just performing destructive changes on their own...
In the end, they ditched us, and we were glad to be gone (they bought out their own contract). Sadly, he got his way, changed his title to "lead tech director", hired a team, and their site went from fairly slick to looking like something from Geocities. That company no longer exists, and sadly, I can't remember his name so I can't see where he failed upwards to.