The article you read is correct. If you give pages that have little content on them to Google to index, it can hurt the overall SEO of your site.
Pages with so little content are what Google calls "thin content." If they appear in Google search results and users click on them, they are likely to be disappointed. Users like to land on pages with enough content to answer whatever question they had when they searched. It is unlikely that a profile photo and social media links are going to answer any questions. Users would probably be better served by visiting the social media sites directly.
This would hurt your site most if a user created a profile name that is a common search term and you site has little to do with that. For example, somebody searching for "stackexchange" would be very confused when they land on a user profile page on your site and would quickly leave unsatisfied.
Google has algorithms that detect when a site has lots of thin content and more algorithms to detect when users are particularly unhappy with search results on which they click. Allowing these pages to get indexed is likely to hurt the SEO of your entire site, including your pages that have lots of good content.
Your XML sitemap is meant for pages that you want to have indexed. Since these pages shouldn't be indexed, they should not be included in your XML sitemap.