No, in this thought experiment, when they have MagSafe, they charge only via MagSafe.

The thought experiment is intended to be the same as reality, just in the opposite direction.

That's what my last sentence is for. If they go pure-magsafe and get rid of all USB-C charging ability then they deserve the complaints.

But if they add magsafe while also having USB-C charging then it's much better than either option on its own.

And keeping USB-C charging does not require extra ports, because you need the USB-C ports anyway to do USB stuff.

The question isn't whether they deserve the complaints, or about the minutae of charging, but whether people think that going from X -> Y is bad and going from Y -> X is also bad. If so, they're just being change-averse: ignore them.

In general it's a good thing to think about.

But you were using it to make an argument that the complaints were invalid.

So I'm going to reply to that specific argument, by pointing out that when Apple changes the IO ports to USB-C and enables USB charging, it does not require them to remove the magsafe port.

In other words, apple went X -> Y. But adding Y reused IO ports and could have coexisted with X. Even though Y might be better than X, it was a false dichotomy in the first place.

There's no need for MagSafe if you have USB charging. It's redundant.

It also entrenches the old standard rather than making way for the new one. If you have a laptop with both USB-C and MagSafe, and you need a second charger, you might buy a MagSafe charger if it's cheaper or to use with an older Macbook. Whereas without MagSafe, you'll buy a USB-C charger — the new technology.

If you want to do a transition, you have to go all in. Having both the old and the new port merely delays the transition, causing more pain in the long-term. Get it over with.