It makes it easier to divvy up into groups: halves, thirds, quarters, sixths (vs. just halves and fifths). Makes doing math easier in the head (fewer digits, checking for divisibility are the big ones).
Some info (warning: they are trying to convince you it is better than decimal, so you are not going to get a balanced argument there): https://dozenal.org/drupal/sites_bck/default/files/DSA-DozenalFAQs_0.pdf
A few features I would love to see:
A way to view groups of multiple communities in a single feed. Like a multicommunity. A workaround right now is to have multiple accounts, which is less than ideal.
A way to view content from multiple accounts in a single feed. Like a universal feed.
An easier way to have the same settings apply to multiple accounts.
A way to block instances or communities.