opium poppy plants also have important uses, but making heroin is not one of them

The differences between Morphine, Diamorphine (heroin), Oxycodone, Hydromorphone, Oxymorphone, etc is all very very minuscule. Once they get into the bloodstream they cross the BBB and bind to mostly mu (but also delta and kappa) opioid receptors, and activate them. Do enough of this activity by any means and they will downregulate, temporarily disabling themselves, which both (A) makes the user's "baseline" increase, which is why they go into withdrawals if they stop using, and (B) requires more of the drug to achieve the same amount of activity, which is how tolerance increases. This is simply the body attempting to keep homeostasis. After a long enough period of abstinence, the receptors with upregulate and turn themselves back on, causing withdrawals to cease and tolerance to drop back to zero (Which is why so many users die after periods of non-use: They think they can instantly go back to their old dose)

There are several "weird" opioids out there like Buprenorphine which has an odd profile that gives it a ceiling, and I'm not including fentanyl and its derivatives because of the extremely reduced half-lives.

But the point I'm making is that all opioids are fundamentally the same thing, none are more "evil" than others. Its mostly the social stigma and black market's choice of product that makes diamorphine users fall so hard into the dark side of addiction. If it was prescribed in hospitals and no longer popular on the black market, (And indeed some countries have diamorphine as a standard pain reliever for acute severe trauma), it would have the same reputation as "medical" opioids rather than "street opioids"

That's why Purdue has to pay some $8,000,000,000. They knew oxycodone would have the exact same effects as anything else with that profile of receptor activation, but instead pretended it somehow has far less to none of the addiction potential of prior pain relievers in that class. If any pharm claims they've found an opioid pain reliever with no potential for abuse, ask them how it prevents receptor downregulation. Because even subutex (buprenorphine) has the potential for abuse if your tolerance is below its ceiling dose, its just much safer because that ceiling is usually well below the LD50 even in opiate naive people.