Crackdowns on "pill mills" and "overprescribing doctors" is what denies people a safe and legal source of pharmaceutical-grade opioids and forces them onto the black market of illegal, overpriced, and fentanyl-contaminated opioids.
Also crackdowns on "over-prescribing" invariably lead to people who experience chronic pain being denied medical access (or being subjected to extremely invasive and degrading treatment to weed out "drug seekers").
The DEA cracking skulls over opioids and investigating doctors is literally the only reason illicit fentanyl even is a thing. I am so very doubtful that skull-cracking and door-kicking will miraculously work after decades of it not working.
Do you want even nastier and even more potent (per unit volume) opioids than fentanyl? Because more prohibition (and yes, investigating and prosecuting doctors is absolutely a component of opioid prohibition) is just gonna give that result.