this only really works because a lot of people post an unhinged amount of personally identifying information
a couple of examples:
a communist youtuber who took great pains to anonymize himself posted about his uncommon and registered profession using the same geographically notable username as his youtube account
a former admin of hexbear posted about their family coat of arms and their job using the same reddit account that they used to moderate r/chapotraphouse
hexbear maintains an embassy on the grad