That’s because the articles normally deal (but in-depth) with just one particular aspect of the configuration, and suppose that the reader can combine the information for different aspects to match his particular scenario.
In the /interface bridge vlan section, the bridge itself must be listed as a tagged member port of itself only i you want to be able to place an own IP interface of the Mikrotik into the VLAN (by means of /interface vlan interface=my-bridge vlan-id=X.
Again, there are tons of other bridge- and vlan-filtering-related aspects to be fine-tuned, but the above is the minimum to make it work.