They were never "purchases" and it's more that the terminology has been faulty and misleading, more so than the business model. The rank-and-file consumer wanted to believe that "purchasing" something was permanent, but the metaphor is leaky. If I purchase a table from Ikea, then I take the kit home, I assemble it, I store the table, I maintain the table, I clean the table, and I can keep the table around for as long…
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.