No, what pressing the wifi icon button on every single wifi-capable phone ever made until iOS 11 is to turn off wifi. Not just temporarily, but specifically until the user decides to turn it on again.
This is how it was even before smartphones. Android keeps wifi location scanning and various other things running, even if you turn off wifi, so it actually accomplishes what people want: to turn off wifi networking until they turn it on again.
But that's just not how human goals actually work. Nobody - except maybe a wireless radio engineer - wants to "turn off wifi". Nobody has that as their actual goal - turning off wifi is a way to accomplish some goal. That goal might be "make the internet work better (by using LTE instead)" or maybe "stop distracting me with notifications from the internet" or something else. But "turn off wifi" doesn't make sense as a goal in and of itself, and so Apple is trying to do something that better maps to what people want.
Now, whether they've done so correctly - both from the perspective of what actually happens, and how it is communicated to the user - that's certainly an issue and it's clear they haven't executed this well.
This is how it was even before smartphones. Android keeps wifi location scanning and various other things running, even if you turn off wifi, so it actually accomplishes what people want: to turn off wifi networking until they turn it on again.
The change made in iOS 11 is a clear regression.