So it has a <4000mAh battery? Those are some expensive magnets.
There are some sensible justifications to those metrics for battery health and charge efficiency. Stopping charging at 90%, limiting battery-based wireless power transfer to 5W instead of 15W, limiting charge levels when the devices get warm, charge management software to protect battery health when plugged in for long periods of time, charging more slowly when you don't need a fast charge, and charging the iPhone before the battery pack are all features with good technical reasons for doing them instead of technical limitations.
The naive approach of always providing 4.2V at as much current as the cell can take is bad for batteries. Apple has the required vertical integration and ecosystem controls to do some of these things that may be confusing.
I'm not disagreeing that it's not an order of magnitude more expensive than a comparable USB battery pack with larger specs.
More on-point with what I think you meant, cellphone fast chargers are usually putting 1C into cells below 75% when thermal conditions are met, which many consider to be stressful to li-ion chemistry. I do think this is ignoring that 1. Better charge standards like VOOC have higher efficiency and so lower thermal load, and 2. cell chemistries have improved iteratively to reduce internal resistance, again reducing heat.
Where manufacturers differ is how they deliver and convert that voltage inside the phone/device. Some of the designs (qualcomm quickcharge) dump a lot of heat stepping down a higher voltage while the earlier mentioned VOOC tries to match everything inside to meet a desired rate of charge.
Temperature is the big enemy followed by dwell time in the saturation zone. (over 80% state of charge, getting worse over 90%).
I genuinely don't know - the only magnetic charging I have on my 1st gen SE is through a dinky little adapter that plugs into the Lightning port, and since those adapters also come in USB-C and mini-B I can't imagine Apple ever getting close to the kind of interoperability they provide. I'm sure I'll have an iPhone that can do inductive charging at some point, but God alone knows why I'd ever bother using it.