Today you can restrict organization creation for proxy voting so your team can only select from pre-defined organizations. However, you can still create new contacts associated with the organization. Many teams have custom fields and contacts connected to other systems to validate those idea contacts.
Better idea association and contact management
Like organizations, restrict the ability to create new contacts when submitting a proxy vote.
In Settings > Account > Organizations there is a new option to disable the creation of new contacts during proxy voting. This will prevent users from creating contacts that did not come from your official integration or sync process.