It shouldn't unless you're very careless. A tag that just updates all of the settings files and restarts the services should have the same effect as the full playbook run.
And if you add a new machine to the cluster, which hasn't gotten all tags run against it? Or of a machine was temporarily offline when a tag was run, or...
There are many potential situations where not running a full inventory against a running machine results in a machine not being properly configured.
