I was talking about losing weight, and keeping the weight afterwards.
Of course it's about energy intake versus energy consumption (possibly also the metabolic effect of different foodstuffs). And of course, you have to adapt the regime to what works best for each person. If it's impossible to get a person to excersise, then by all means go for diet only. And if meticulously counting kJ's work for you, great. But it doesn't have to be that complicated.
FWIW, I am impressed by you losing 30 kg.
But to say that excersize is of minor importance is wrong. There have been a lot of studies of weight loss regimes, and again and again we find that diet combined with excersise in general give significantly better results than diet alone. It is considered and important factor for weight loss. At least as long as we're talking about healthy regimes.
Maybe you were only sharing your experience, and if that's the case I have no issues with what you wrote. But when you say:
"Excercise is a relatively minor aspect of weight loss."
and
"The most challenging aspect, really, is keeping the numbers straight in your head. Every single thing you put in your mouth, needs to be calculated precisely"
I interpreted it as something more that that, that you were saying something like "this is how it is", and not "this is my experience".