Background noise can distract your audience from your presentation. This is true during a live presentation but background noise is also distracting during a webcast presentation.
Asking your audience to be on mute can avoid background noise from them. However you do have to consider that this could have a limitation effect on the level of interactivity. It is only one click to unmute, but it could withhold some people to speak. The second part is background noise coming from you as presenter during the webcast presentation. Also try to avoid this. Try to find a quiet room that doesn’t create too much echo. Close the windows to limit noise from outside that could be interfering. Another good way is using a high quality microphone that only picks up your voice and is not so sensitive for background noises.