Right. And when 5 came out if it was not backward compatible you can't use it. Mandating a specific plug based standard would hasten teh move to wireless charging and OTA synching/transfer.
Sorry, I should have been clearer: I consider USB4 the base starting point for year zero. Right now, there is no predictable way to know which features under the "USB" umbrella are supported by any given Android device with a USB-C connector.
- I don't think (m)any have Thunderbolt data transfer, they mostly have different variants of USB 3.* (meaning data transfers could top out anywhere between an effective 500MB/s to 2.4GB).
- There is no consistent support for USB-PD, and that too has different specs that can affect charging speeds and battery health.
- There is no consistent support for alternative data transfer modes besides such as DisplayPort and PCI Express.
By starting with a solid base feature set, we're not preventing future phones from building on top of that or implementing USB5 when that arrives, and USB has been fantastic about supporting legacy USB data transfer standards so, for example, you can connect to a USB 2.0 port on a PC and still expect data to transfer, if much slower.