And pharmacy vertical integration is an easy way for them to get around regulated profit margins. While if your profits are capped at 15%, the only way to increase them is to increase premiums as a result of increasing providers costs (which the insurers can and absolutely are doing, of course), if you own the pharmacy supply chain, you have freer reign to increase those prices.

Healthcare is one where vertical integration can be really profitable, even at the smaller scale. I used to work as a paramedic, both local agencies and private. The private ambulance company I worked for started when a man who owned a nursing home realized how much money the facility was paying for ambulance transports, so he started an ambulance company. He realized how much his ambulance company was paying to industrial/medical gas companies for oxygen, so he started a medical gas company. And so on. And went from his one small nursing home to his daughter having a $100M empire by the time he died 30 years later.