With the introduction of version 2 or 3, it was no longer needed to explode components to edit them(!)
With the rightclick > Select > all on same layer, you could easily group them again.
This relic from the past can cause various problems like misunderstandings of what is visible, but the main issue is when you start editing raw geometry that has several tags. It doesn’t prevent merging and it is also unpredictable what tags the geometry gets when extruding or intersecting (in combination of the setting in the tagpanel of the active tag)
There are no performance issues when geometry ‘inside’ objects have different tags. It’s better to have them all on one tag specifically for organizational reason’s, maybe, but there is no benefit in having it on another than the tag of the container.
For this reason, why not have them untagged in the first place.
Copies of Dynamic Components do behave the ‘oldfashioned’ way, btw.
But that might be another can😀