I mean, that’s the healthiest charger for the phone. I know you’re trying to say “give me a stronger charger”, but for others this is actually a selling point - I don’t want strong chargers, I want a well built weak one that preserves my battery.
You can get the best of both words with good power management. Fast charging can be disabled on my phone. I also know some laptops where you can limit the charge to ~70%, intended for case where it is always plugged in and you rarely need the battery. Some phones try to be smart, taking into account the time you set up the alarm for instance.
The idea is to have fast charging for emergencies and slow charging for regular overnight charging.
And the thing you plug into the wall isn't actually a charger, it is a power supply. The real charger is in the phone, and that's the one that decides if it needs fast or slow charging, taking into account what the power supply can deliver.
I know there are plenty here who agree with you, but for at least 98% of the population its just a crappy old technology by company who is charging too much over it. They don't understand technical details and they don't care. A phone who can charge in 30 mins vs 2 hours is a major selling point though.
Most people change phones every 3-4 years due to many reasons, physical attrition of hardware being one of it, battery being another, overall hardware not being good enough (speed, capacity) being another.
Almost nobody cares if they can save 5% of battery over that time by charging slowly. Heck, I know I don't. It would be a different proposition if one would lose say 50% of capacity, but even folks in this thread confirm that's not the case for same hardware.