Excessive parasitic draw while the car is sitting, coupled with short drives where there is never adequate time to return the battery to near full.
I have data from my own vehicle in terms of how long it takes the charging system to return that which was used to start the overnight cold engine.
It is about 45 seconds when the voltage regulator is seeking and holding 14.7 volts.
This is determined by amperage. I was holding the battery at 14.7v and noticing how many amps were required to maintain that voltage before starting the engine.
After starting the engine, once amps taper to that same level at 14.7v, the battery is as at the same state of charge as before starting the engine.
It took ~45 seconds at 14.7v on my vehicle for this to occur. This is with a precise 500 amp 50MV deltec shunt measuring amperage into and out of the battery.
So unless one drives for less than ~45 seconds, short trip driving is by itself not the cause of premature battery failure, but short trip driving has no chance of returning a less than fully charged battery to full charge, and with ideal charging voltages, which NEVER occur in 99.99% of vehicles on the road, a lead acid battery cannot get from 80% to 100% charged in less than 3.5 hours.
I know that many will say it takes 5 or more minutes to return that which the starter used to start the engine. I can;t see this happening on a modern fuel injected gas engine, but likely was true with carbs and longer engine cranking times and perhaps multiple starting attempts being required.
Likely it took longer than 5 minutes in such circumstances.
Since fuel injection and quick starting vehicles became the norm, batteries have become lighter and lighter in the same size group, with thinner and more fragile plates more susceptible to shedding material. This makes them more susceptible to degradation when cycled, even if only to 80%, and more susceptible to heat and vibration.
Vehicles today have much higher parasitic draws, which make it harder to get the battery fully charged especially when they sit unused often, and many vehicles are intentionally keeping the battery at lower states of charge in order to squeeze out some executive bonus money when CAFE standards are met.
Marine batteries are more durable than dedicated starting batteries when cycled deeper, but come nowhere close to actual deep cycle batteries in this regard. A group 27 starting battery in 1970 would likely be 15% heavier than a group 27 starting sold today, perhaps even heavier than a marine group 27 which can be as high as 62 Lbs for a marine and as light as 48lbs for starting.