Real rock is stunning, there is no doubt about it! That is why we go out into nature and take molds of every gorgeous rock face we can get our hands on. That being said there are serious limitations, especially when you cut it/ break it up and then try and reassemble it to match a natural rock wall or waterfall. We use real rock on smaller ponds and waterfalls, or fountains that make sense, but as soon as you start trying to move into larger retaining walls, or water features real rock doesn't cut it.
When you go out into nature it is very rare that you will find dozens of mid sized boulders stacked on top of each other to form a wall. That is why we take giant moulds (9.5' x 40' is our largest) so that your retaining wall, or waterfall, or grotto can look as nature intended but with a few extra luxuries like variable speed pumps, lighting and cup holders.
We have seen many real rock projects next to a pool that have been "seamed" together to try and mimic what artificial rock can do but these have a tendency to shift and settle leaving you with a tired waterfall that likely leaks. Our faux rock work is built to last, with the minimal maintenance required (usually reapplying concrete sealer every few years and occasionally recoloring if you don't have us reapply that sealer;)