I didn't say it wasn't. We're suggesting this as a power they should have, not something they should do with a swinging axe. What we have in mind is cases we've been through where the first offer you get is, "We'll amend the headline online only". Then you get the offer of "We'll print a letter from Full Fact disagreeing with our article but we won't change the article or admit there was anything wrong with it". Then you get page 12, then you get page 6, then you get page 4, then you get page 2. All of this, rounds and rounds of correspondence, weeks between them, takes forever, deeply tiring. And all of this, of course, after the actual inaccuracy has been accepted. At this stage, you're just arguing over prominence.
You've already talked about the PCC should just be able to say, "This is how prominent it should be". Maybe that's the right answer, but at the very least they ought to be able to reject derisory offers.
I should highlight in that sequence the letter because the code says you have to correct inaccuracies. A letter from somebody else disagreeing with your article isn't correcting an inaccuracy, even though it's routinely accepted as a method of correcting a general inaccuracy.