All participants are leaders when joining a Lync 2013 conference
I have had a few customers ask me recently why all users that join a conference can do things normally reserved for admins or originators. In reality, its not all participants that are designated as presenters...it's only the participants in the company\organization. The default meeting options for all users are set to "My dedicated meeting space". The default options for this meeting type allow all attendees from the company\organization to be presenters.
Can this setting be changed with set-csmeetingconfiguration? Yes and no. You cannot change the options for "My dedicated meeting space". You can force having only the meeting originator as presenter if you change the assignedconferencetypebydefault to "false" and then change the deignateaspresenter property to "none". This will make all meeting the secure\private type and use a different meeting ID for all conferences. This may not be suitable for some environments.
The other option is to educate users to click "Meeting options" in Outlook when creating the Lync meeting. They can then select the presenter options that fit's the situation. This option does create a one off meeting ID as well, the difference is that the user only selects this type when needed.