Pretty much, that’s the explanation given back then.
Iirc it was phrased more that the risks of complications from removing the less healthy ones and all the blood supply issues that go with that complicat e the surgery in both time and possible unwanted outcomes. So damn near exactly what you said :)
There’s times it has to be done, but to the best of my knowledge, the majority of cases, the kidneys aren’t doing anything bad, they’re just not working right.