I do not agree.
The sun is necessary for algae. So it is necessary to try to repeat.
The advantage of algae is that scrubber on it grow many species of algae, and most importantly, they have a different color!
Color indicates a favorable light spectrum.
An experiment - one grid to put two fluorescent lamps 2700K and 4100k and saw the difference in the types of algae growing in a wide range spectrum.
Algae grow those for which an enabling environment and the light! (close to nature) Different species of algae in different ways to change the composition of sea water.
I understand your point and I had planned an experiment quite some time ago in order to try a few of these ideas out - a bandwidth test, essentially. Line up a bunch of scrubbers with various active bandwidths and a stock solution of water + fertilizer or something like that, and see which grew best. But I just haven't had the time.
What I can tell you is that while you do not agree, and that is OK, I have 3 scrubbers on tanks I own personally or help to maintain that run scrubbers with only 660nm and 445nm and they work extremely well. 2 of them run only a scrubber and are moderately to heavily fed, no algae in the tank, no nitrates, and very low (and stable) phosphates.
On top of that, literally hundreds of scrubbers out there running the exact same setup I run - only 660nm Deep Red and 445nm Royal Blue - and they do the job. I'm not saying that adding other spectra is completely unnecessary - I'm just saying that my personal opinion is that the additional spectra would very likely only get you another small percentage increase in production - likely, something along the lines of 5-10%, maybe as much as 15%.
On the other hand, if you look at CFL and T5HO scrubbers which are running 2700K-3000K lamps, these grow algae better than their counterparts running 4100K, 5000K, 6500K, etc. These combinations of fluorescent sources have been tried, and that's why the 2700-3000K was settled upon as the baseline to use for algae scrubbers. Because it worked better in real life applications.
Furthermore, what I have found is that LED based algae scrubbers that run 660 and 445 grow nearly exclusively green hair algae, whereas CFL scrubber running a wider-spectrum 2700K lamp (which contains a variance of spectra due to the nature of fluorescent sources, i.e. phosphors to shift UV light into visible/useable spectra) tends to grow a lot of other types of algae, like yellow spongey stuff, or gooey growth, or dark growth, etc, unless it's very closely matched to the system (i.e. tank, flow, lighting, etc are all in 'synch'). The GHA is what grows the fastest and is what "we" generally want to grow. My opinion on the LED growth is that the bandwidth is focused down to what is primarily needed to grow GHA (660 mainly) and I have proven this to myself 100x over. The extra bandwidth that is provided by fluorescent sources seems to actually cause the growth that I consider "nuisance" growth. That yellow gooey growth, etc, is not filamentous, so it grows in a sheet/mass and blocks light out to lower layers which can drastically reduce the effectiveness of the scrubber's filtration capability.
Early on in the experiments with LED algae scrubbers, people did try to use a mixture of different LED so try to achieve that wide-bandwidth mixture. They used warm whites, neutral whites, 630 reds, 660 reds, cool whites, blues, etc, all mixed together. They pretty much all came to the same conclusion and that was that all you really need is (primarily) 660nm Deep Red to effectively grow algae for the purposes of the algae scrubber.
Also I don't feel that plants are exactly analogous to algae given the rather unique application of the algae scrubber.
