Yes, the battery doesn't charge to "dangerous - could explode" levels. But they very much do still charge to levels that are damaging to long term health/capacity of the battery.
Yes, they tune the batteries so that 100% isn't the absolute cap. But even with that accounted for, many batteries will be above values that would be considered good for the long term health of a lithium cell. 80 percent on most phones is still very much at levels that are considered damaging to lithium batteries.
To put it another way, the higher you charge a lithium battery, the more stress you put on it. The more stress you put on it, the fewer charge cycles those components will hold. It's not like there's a "magic number" at 80 percent, it's just that the higher you go the worse it is. Yes, some manufacturers have tweaked charge curves to be more reasonable. But they've also increased limits. Many batteries now charge substantially higher than most people would consider sustainable.
And after such changes, 80% lands pretty close to the general recommendations for improved battery longevity. Every percent will help, but it's not a hard and fast rule.
Calibrations have gotten a little better in some ways, but all you have to do is look at basic recommendations from battery experts and look at your phones battery voltage to see that almost every manufacturer is pushing well past the typical recommendations at 90 or even 85 percent.
That's why Pixels and some others have a "smart charge" feature that will wait to charge your phone until just before your alarm time so that it will finish right before you take it off the charger.
I honestly don't understand why people have such trouble with this. I can throw my phone on a charger when I go to shower and it's at 80 percent when I get out, and that's enough for my day. I could leave it while I get dressed and eat or something and it'd be at 100 if I needed. I don't need my phone 24 hours a day. And there are many points in my day where I'm not using my phone for an hour that I could spare to charge it. I don't need to leave it burning away permanent battery capacity for hours and hours every night.