While there is some truth in this, you should have access to the rifle you intend to load for so that you can work up a load specifically for it. This is no different then allowing someone to shoot your handloads in your own rifle. I have the load data for the specific rifles I load for, regardless of who owns them.
On the other hand, I don't want other people having access to my loading bench. A pal of mine allows a couple of other people to use his loading room. Arguments about who owns what components, issues related to spilt primers and powder and general clean up, cases stuck in dies, and dealing with the bruised feelings that come with communal loading are things I would just as soon avoid. If someone wants to come in and watch for an hour to see what is involved in the loading process, no problem. Keep your hands in your pockets and I'll do my best to answer questions as we move along. If that doesn't work I can help get you started with your tools on your loading bench, and I'll keep my hands in my pockets.