MP4 works fine, but different ways of creating/editing/preparing video all have different ideas about how to produce a video file, and the people operating them don't always have the technical background to even know there's a difference. YouTube offers a simple solution: drag any video file in any weird format to the upload modal, and you never have to think about it.
You're right that all the major video hosts offer it too, and I think GCS/AWS/Cloudflare all have APIs for it, but YouTube does it for free without requiring you to have any clue about all this stuff.
Fair, but in my view if you have engineers implementing your marketing homepage they should be able to do this for you just like they write the HTML and CSS for you and figure out the deployment.
And if the marketing team uses Webflow or Framer or something like that, maybe those tools should add native support for dropping in videos without needing YouTube to make it equally simple, just like they make the rest of the development of the website simple.
Yeah, I've very recently had issues with mp4's only working on desktops/firefox/etc due to the wrong encoding or container or whatever not being supported. hvec vs mpeg-4 maybe? Had to mess with ffmpeg arguments multiple times to get it right. Meanwhile if you put it on youtube it will work 100% of the time.
https://blog.youtube/inside-youtube/new-era-video-infrastruc...
You're right that all the major video hosts offer it too, and I think GCS/AWS/Cloudflare all have APIs for it, but YouTube does it for free without requiring you to have any clue about all this stuff.