We'd like to have Webex support joining a meeting from multiple devices and as long as you're logged in under the same account it would recognize that it is "you" from both places and treat you as a single attendee. This is useful when you want to view or share content from a different device than your audio or video is sourced from, or if your audio is sourced from a different device than your video. That way your video will "spotlight" you when you speak even if your audio is from a different device.
People don't always join from a single device. They may want to use a mobile for showing their video while attaching to the meeting for content sharing from a desktop. Or they may be using a virtual desktop that currently doesn't support content sharing optimized for video and need to attach a second device for that. This provides a better user experience for people that have unique connection requirements that differ from those that connect from a single device.