Hey @genefish,
@mcneese.chad is right. We do use heart rate data in AT (Adaptive Training) and AIFTPD (AI FTP Detection) when we have it. @alexstenerson
Personally, I go back and forth between wearing a HRM and not. For me, it does depend on how I’m feeling and what type of ride I’m going on.
For Endurance or Z2 rides, I tend to focus on HR more than power, as I find that on longer rides my power will start to drop for a given effort and effort is what I’m focusing on in those situations.
In addition to that, HR can be beneficial to compare to your power as a way to see your body’s response to certain types of efforts over time both short and long-term.
You can also then factor in conditions such as heat and altitude as well to see where your performance may start to dip. This could then serve as a good benchmark when trying to improve in those conditions with different hydration or cooling techniques (etc.) as well as a way to see if you’re adapting to those conditions over time.
Lastly, if I’m feeling particularly fatigued I tend to wear a HRM and pay a bit more attention to it to monitor what’s going on inside alongside my overall RPE to help ensure I’m not overdoing it. It’s usually pretty easy to see if my heart rate is considerably off from normal which tells me to take it easy or call it a day.
Power is a great way to read the data of the actual work you’re doing in watts and kilojoules, but doesn’t tell the story of your internal stress which is still really good information. 
P.S. If you haven’t already, I’d recommend finding your lactate threshold heart rate and basing your zones on that. It’s likely going to give you the best data to follow.