Supply bases, to make an anology to airlines, are like airports, all things operate from them. They differ to say a maintaince facility which is often located away from operational areas.
In other words, it's like Qantas owning the entire Sydney airport. If Qantas owned Sydney airport it would have a competitive advantage.
MRM built and owned Dampier supply base. MRM had a competitive advantage, by the vision of its founders it created the supply base. It no longer owns the base.
MRMs own website is a good source of the history. It's worth researching the old stuff to see the vision. It's also worth looking at the 2014 Jaya deal to see where it all started to go wrong.