As mentioned here: https://big.ideas.aha.io/ideas/APP-I-3020 I can create a pivot table that totals the number of ideas submitted per user, but sorting appears to be handled alphabetically - first by portal user and then by Aha user, vs by total number of ideas created.
Thank you for your idea. This is currently possible. After setting up your pivot to calculate the total number of ideas submitted, you can then sort the idea created by field using this value. The attached screenshot shows where you can find this.