I agree with you too, Veronica - full on true that each person's max heartrate is a setpoint and very individual - not something that you can strive to increase or train to make it higher as if it's better when it's higher. There is a great little book that I used to learn more and do my own max HR test at home, before I had it done professionally. It's by Sally Edwards and I think the title is something like Heart Zone Training. There is a "step test" that was very accurate...only 1 beat off from what I got as a max when I was tested for my max heartrate on my bike professionally. She also has sport-specific information for cyclists, triathletes, runners in other books and the heart rate cycling book has some good workouts too.
I usually refer more to my heartrate than any other cycling data now while riding...it gives plenty of data for how the training is going, and how I'm feeling is reflected in the percentage of max hr and average, etc. during each ride...I think it's really an interesting window inside and a great indicator of improvement, fitness, etc.