I need to do 2 changes every time I change a format string - I need to remove the symbol representing it's placement and then I need to remove the argument passed to .format.
Also old formatting does not easily support arbitrary expressions in the placements, thus in order to get those you need to change the arguments passed to the .format.
f-strings get rid of those issues altogether. What you're showing is whatever you have in the brackets - 0 indirection and thus less margin for (unnecessary) errors.
That said, I also struggle to understand how you’d claim parent clearly not using Python enough, when your description of str.format shows a lack of understanding to it yourself. One of the advantages of str.format over %-formatting is exactly that you do not need to modify the arguments passed to str.format when removing components from the source string:
>>> '{0} {1} {2}'.format('a', 'b', 'c')
'a b c'
>>> '{0} {2}'.format('a', 'b', 'c')
'a c'
>>> '{x} {y} {z}'.format(x='a', y='b', z='c')
'a b c'
>>> '{x} {z}'.format(x='a', y='b', z='c')
'a c'
It's not the string that most of the developers care about, it's the presence of the arguments to that string. The issue they are solving is "I would like to see A, B and C", rather than the issue of "I have provided A, B and C - would you please hide B from the view".
>> But again, this doesn’t matter to parent’s argument. Nobody is arguing with you that f-string is better than alternatives for what it can do; we are trying to tell you that there are things it can’t do, and you did not get it.
Please elaborate on what the f-string can't do? You have not provided the answer in your post. In my opinion, the only issue f-strings haven't solved is capturing the arguments in lambdas (before interplation) instead of their direct values. You, on the other hand - do not provide a clear explanation.