Hoi,
You do not get it. There are many properties. Consequently the scale of things is substantially different. It has been demonstrated that languages will have homonyms and consequently it is NOT a good idea to use labels or whatever you call them for properties. You can use them as long as internally you use the P-number. You can use a text as long as the combination of label and description is unique. This combination may be useful.
At the same time be aware that property labels will be wrong and will need to be changed at a later date. When this presents a problem for the comparison with external sources, it is tough. It is best to indicate this from the start.
The argument about what happens in MediaWiki is secondary. And sorry that not everyone cares or knows about that in your way. The point is very much that at the scale of thousands and thousands of properties it does not scale. This point has been made plenty of times by now.