This topic has been floating around for years and I’ve seen it discussed (and misunderstood) to death on sites like Android Central and even on Mac Rumors.
So I’ll be the first to agree that all of the OEMS are doing a terrible job explaining to the general public how their implementation actually operates AND that SAFELY and EFFECTIVELY charging the battery in your smartphone is FAR more complex than most realize.
OTOH web sites such as this, who I’m almost certain get briefings from those same OEMS on new hardware (like we do) are being irresponsible or neglectful in their reporting on this, likely because they go for clickbait.
In this case, the very first thing that Google said was that the fast charge was designed for was “quick boosts” or “top offs” when you did something like neglect to plug in your phone the night before.
OnePlus, who has somewhat led the way with this via their “warp charging” used to also be very good explaining this, but since they became part of Oppo, not so much
And if you need any reminder about how complex and fraught , battery charging when you do it wrong, you only need to look to Samsung and their Note 7 and S6 trials.