There's a bunch of internal types like decimal vs newdecimal, binlog started out statement based until they realized uuid generation is random so added data replication on top. CDC offset started as filepos before GTID was made so offset could survive failover
There were aspects of the design I appreciated (logical slots in postgres have a bunch of drawbacks avoided by just appending to 2nd serial log which has an expiry date instead of tracking clients' offsets), but developing against protocol you learn to not try build a consistent mental model