These differences are also not exposed in a user-friendly way: I know I have to plug the charger cable directly into my MacBook, and I know, in broad terms, why. But there's no alert telling a naive user they can't (actually they can, but shouldn't) plug it into a dongle and plug the dongle into the MacBook. It appears to work. Eventually you might discover that it works poorly. It's a fake simplicity. Not putting device-specific charging into USB-C would address many of the hidden gotchas, and would have maintained the cleverness of mag safe charger plugs.
At best you can say you won't damage equipment in the process of discovering the quirks of USB-C. Except, of course, for the cheap not-up-to-spec cables that might cause damage.
I’ve been using computers since I was 7 in 1985. I never had to think about the chain of custody of my power cord until very recently.
IMHO, regulatory bodies should be taking a hard look at multi-use cords over a certain power level. It’s literally a matter of time before people die as a result of some fake Amazon cable.
Could explain why you need to plug power directly into your MacBook Pro or MacBook? I use both, and was unaware of this. Any source would be super helpful too.
You may not get the full wattage through a dongle. For example, the Satechi adapter with pass-through charging (recommended by The Wirecutter at https://thewirecutter.com/reviews/best-usb-c-adapters-cables...) is limited to 49W: go to https://smile.amazon.com/dp/B01J4BO0X8/ and search for "Important Notes". 49 watts may be enough for many uses, but (as I discovered recently) not when running a job on all the cores of a 15" MacBook Pro.
Now, presumably the designer of this dongle had some reason to limit the power output. Perhaps the heat dissipation is not enough (the dongle gets pretty hot even when using it just for USB and HDMI). What if some other manufacturer is not so careful and allows negotiating more power through a similar device?
My MBP wants an 87 watt USB-C charger. If you read the product page for the charger, it recommends plugging directly into the MBP's USB-C ports. When I tried charging through the dongle, the battery would charge slowly, or drain a bit when, for example, running gradle builds.
Say what? Most dongles with usb-c ports sold so far are specifically designed to relay power. If that's not working for you then you may have gotten a bad dongle.
I think that's the point. With off-the-shelf aftermarket parts, it's not always clear if you're getting something that can provide clean pass-through power or not. Or even if that's something you should be worried about.
At best you can say you won't damage equipment in the process of discovering the quirks of USB-C. Except, of course, for the cheap not-up-to-spec cables that might cause damage.