VLC is great and I use it personally. But it's too complicated for my kids and doesn't integrate with the parental control system. And also, millions of people use Apple's apps to consume content and my objection was that they made that process worse.
SMB, FTP, Plex servers, all the well known cloud services, even a built in web server so you can connect any web browser to your device's IP address and drag and drop files onto the device.