I would be careful not to confuse correlation with causation here. Most old people have medical conditions. For example, about 75% of older people have high blood pressure [1] so seeing a 75% rate in the virus fatalities should not mean much.
I suspect age and immune function drive mortality, and the other factors are merely along for the ride.
When I studied medicine 15 years ago 130-139 mm Hg was not considered high blood pressure. We were young students and we were toying everyday measuring our blood pressure. Most males had over 130.
"The prevalence of borderline hypertension was calculated by determining the number of persons who had systolic pressures between 140 and 160 mm Hg or who had diastolic pressures between 90 and 95 mm Hg."
This is more inline with what I've been thought in med school in my time.
What were the most common pre-existing conditions?
"More than 75% had high blood pressure, about 35% had diabetes and a third suffered from heart disease."
How common are those conditions in the United States?
High Blood Pressure - 1 in 3
Diabetes - 9 in 100
Heart Disease - 1 in 10