Shifting a query from one space to another space requires Moderator Authority. Only the space specific moderators can shift the content to appropriate space.
My guess, initially, PM, QM might have also been covered under this same forum. Later stage, separate space might have been opened. But still many people don't have that awareness or because of their urgency, they may be posting in different space. Also new people for SCN can't understand the forum rules about exact space where they need to raise their thread.
Now PLM covers the process of R & D, Laboratory where new products will be developed & their life cycle activities.
http://wiki.sdn.sap.com/wiki/display/PLM/SAP+Product+Lifecycle+Management+(PLM)
In addition to above, total Product lifecycle includes Quality Management of that new product, Maintenance of those Laboratory Equipment, Material Master, Bill of Material for that Product, Project by which the R & D project can be handled, etc., It covers complete business processes of Procuring, R & D, Actual Production, Maintenance of Equipment, Quality Inspection for that Product, etc.,
So, it is not harm to open other topic related queries in this space, still we can use appropriate space to get more & better views.