... and thousands of pages and even more legacy redirects to manage, several new landing pages for campaigns and SEO every week written by non-technical people,

... and thousands of pages and even more legacy redirects to manage, several new landing pages for campaigns and SEO every week written by non-technical people, localized content in 15 languages integrated with a translation backend, integrated e-commerce features, serving different image formats and resolutions for mobile, new integrations with third-party tools every month, etc Yeah, no one is going to manage that with GIT + HTML + CSS.