Sony chose to use the words "purchase" and "buy" on their pages, and hide some sneaky text in the EULA that changes their definition to remove the implication of ownership.

They know that using terms like "rent" or "lease indefinitely" would reduce their revenue, so they squirrel away legal gotchas that no one ever reads to cover their arse. It shouldn't be allowed.

Just because something is legal doesn't make it ethical. Sometimes the ethical thing to do is ignore the legalities, which is why people are fine with advocating for piracy in cases like these.