One thing that @Sarel.Wagner implies, but doesn’t say outright: the Fronius (any grid-tied inverter really) is much better (more efficient) at generating AC than any Quattro / Multiplus + MPPT system could ever be.
I assume he uses most of the power in the day, i.e. immediately once generated, so he actually wanted a Fronius and then needed something to keep it going during load-shedding. The Victron-Fronius integration is top-notch so it’s a no-brainer.
I’m in the same boat @ From grid-tie to microgrid / hybrid backup. (My money-saving is covered, I need something for load-shedding.)
If you used most of your generated power later, i.e. into a battery and then out again, the Victron DC MPPTs are much more efficient at that, and using a Fronius would waste a lot of power. If Time-of-Use (TOU) tariffs become more common I think a lot of people would time-shift their daytime generation into batteries to use during the evening peak. DC-coupled MPPTs would be best at that, assuming you have low daytime load otherwise.
So yes, people can want a not-Victron and then happily add a Victron for another reason 