I didn’t think about the abrasiveness.

However, I think the issue with reverse osmosis is also with the wearing out of parts / maintenance. Also just complexity.

For reverse osmosis, you need to be careful about filtering large particles before hand and often times need to use some sort of oxidizer/biocide to prevent biofilms from forming on the membrane(s)

You also have to worry about the minerals in the water, pretreating it to prevent scale. And the filters themselves are complex to manufacture, and you’ll eventually need a replacement.

I’d imagine the idea behind this design is in its simplicity. You don’t have to filter the water much or pretreat it because you’re mostly running it through large pipes that can handle debris and various pH levels.

If parts break or wear out, you can probably find or even make cheap replacements since it’s mostly just going to be metal piping. You also likely don’t have to get as high pressures as you do for osmosis so you might not need an external pressure system, or if you do, not an expensive one.

You definitely don’t have to worry much about biofilms since you’ll be dealing with super high temperatures and salinity (unless some very specific extremophile bacteria/archaea get in)

So for places that are remote, this design ( if functional), might be a good choice as it will be much more easily reparable and not require speciality equipment. Nor require much specialized knowledge for that matter besides the main idea of “sunlight heats water in pipe, some evaporates, condensed water is desalinated, hot water can be used for energy”