ugh... Try this. I'm chipping at the practice green, and another guy shows up. He chips from the other side, but after he exhausts his cache, he walks onto the green and starts putting them all in. This is at a club with its own practice putting green mind you. He's got this swagger like he does this all the time. Of course all my chips are now barely dribbling onto the green. Finally I just left the rest of my balls and took off. And part off me suspects he did it intentionally to hurry me.
I've got NO problem sharing the chipping green. I also have no problem waiting for people retrieve their balls. But hanging out and putting basically is a nose thumb to the other person. Its saying, "you have to wait five minutes while I practice, or try to chip on without getting near me." If people were meant to chip onto greens that others were putting on, then why is it against the rules of golf?