While doing Start a discussion or Write a document Insert Image option has only single image selection functionality. this limit users to do multiple clicks if he/she wants to upload multiple screenshot file for any issue. this limit person too who is answering the thread.
my suggestion is to either give a multiselection image option from upload image option or multiple upload browse button so that the user can select multiple images in one go. this applicable to attachment functionality also.
As of now in Cloud Customer Connect this is the Limitation, hope this should be taken care of in new platform implementation.