I don't think that's true. (Which is a polite way of saying: sorry, but that's nonsense.)Literally everybody mix their chemicals. not literally but 99%.
By far the most people engaged in darkroom photography that I speak to do not compound their own chemistry. They buy ready-to-go chemistry.
And as pointed out earlier, there is a variety of ECN2 chemistry being sold for small-scale amateur use. Some of it, like CineStill, is really modestly priced. There's not all that much potential for dropping prices further in a viable commercial outfit in a Western country below the CineStill level. Using self-made ECN2 chemistry as a benchmark is misleading because you don't have to deal with packaging, QC, distribution, cost of sales, cost of after-sales support etc. etc. etc.