Here's the thing... In reality, there are actually many factors. We tend to all think that all LI batteries are the same, but there are actually a lot of different battery chemistry options that have different advantages and disadvantages.. One of the main options is a reduced initial capacity of the battery but with a better long-term capacity to the battery. This is independent of your charging habits. All types get increases in longevity by sticking to the 80/20 rule (assuming the manufacturer didn't already factor that into their charging system for you).
With phones, almost all manufacturer's actually charge to 100%, and they use a battery chemistry that gives up long-term battery health for short term gains in capacity. They do this because the devices are small, and people and tech sites alike judge them on exactly how many milliamp-hours their batteries have, how much runtime you get from them, and exactly how thick the devices are down to the 1/10th of a millimeter. Only the numbers for when the device is new seem to matter to anyone, so they're forced to compete by trading off the long term health of the battery.
It doesn't help things much that they certainly don't mind if your phone is worn out in two years.... especially if you don't seem to either.. If anyone ever let it affect their buying decision things *might* be a little different, but generally people don't.
Tesla has done a good job of managing the imminent demise of their batteries by choosing a better chemistry that has a reduced capacity, and also having you help by letting you default to charging to 80% for daily stuff, and you let it know in advance when you're planning a longer trip. They could have had cars that sold with longer range batteries at the same cost, if they didn't care about what the battery life was like for people a couple of years down the road. Instead, most Tesla owners find that years later, they're still not having to think about replacing the battery in their car. When they first came out, *lots* of people were saying that you'd need to factor in having to replace the entire battery pack every couple of years, and that was going to make them not worth owning.
The other thing that isn't talked about here, but that matters quite a bit, is the temperature of the battery. Tesla's manage their battery temps very carefully for extended life. Unfortunately, phones can't really do that quite as easily.
Whether your phone/laptop's battery seems to degrade quickly or not, you can always increase it's lifespan by sticking to 80% max and 20% min... It's up to you whether or not that's a worthwhile endeavor.