When dialed into a meeting, users can press *6 to mute/unmute. Please see https://docs.microsoft.com/en-us/MicrosoftTeams/audio-conferencing-common-questions#what-in-meeting-dial-pad-commands-are-supported for further information.
I thought this was Skype parity, but stand corrected… my apologies. I will investigate presenter ability to unmute attendees with the feature team. Thanks all.