CUSTOM THUMBNAIL when uploading a video

Why did you remove the option to add a thumbnail when creating a post and uploading a video on platforms like IG, FB and LinkedIn? We upload a lot of videos and reels and you expect us to go through every video, change the thumbnail on file manager before creating a post and again… browse on hundreds of videos.
It’s easier to create a post, add caption or description, add video and add thumbnail. Why do you want to make things complicated?