I think the point is that we should not as a general rule recommend people do RO for their entire house. Toilets, showers, and washing machines don’t need RO water and if a lot of people did a whole home RO system we would start to see waste add up.
We live in a water supply area with water one order of magnitude harder than anywhere else in our county.
I'm putting an RO unit in our kitchen to serve drinking and dishwasher needs. Our dishwasher needs descaling after a couple of months of normal use. Other uses (shower, toilets) aren't impacted by our super-hard water, so no RO for the whole house, mainly because of the water waste you note.
Oh. Sure. That will always be so cumbersome we don't have to worry about it. That would be a huge RO system. They don't have a lot of throughput so you'd need a big storage tank or a very large set of filters and a pump I'd think. I'm not at all concerned whole home RO will every be common.
