Yes if all you was using was RO water and no active substrate or root tabsBut Flow without nutrients sucks.
But low nutrients with good flow spreads the limited supply round, good levels of nutrients in tank as a whole and poor delivery to plants leads to issues eg dense stems in areas of poor flow lose leaves an lower part of stem, however good flow maintains the leaves
RuBisCo (and NADPH) happen withing the cells off the plants, however flow is external to the plants , Flow isnt need in air for CO2 as its diffusion rate is 10,000 times faster in air than water. But flow is King in waterRuBisCo (and NADPH) will have a conniption if you say that ; Flow is king only when it carries nutrients
Limiting some nutrients can have fantastic effects, bit like the death and breakdown of leaves on trees in the fall, and some deficiencies can be prolong and still tank looks greatbut we are missing something beautiful
But what is the toxic level for each nutrient and it will be plant specific as wellWe can't willy nilly dose everything as we please. The word excess is misleading. Too much of something will increase the chances that the plant will pick that up (possibly instead of something else? - Mulders). I love what Barr did to develop EI - it's great - and if it wasn't for EI, I would not know what healthy plants look like, nor would I have considered CO2 so deeply. But if you dump whatever the toxicity of something is in your tank (as it will be unique to each tank) minus 1 into your tank and sustain that level for months on end, there will be issues. My Rotala that change immediately after MONTHS of excess potassium is a prime example. My Pogo too.
@ceg4048 dose his tank 3 to 4 times in excess of full EI, he reported the plants never looked better
@Tim Harrison use to dose his with a luxury dose - x2 EI levels - plants looked great. Tim is using more lean doses ATM ( correct me if I'm wrong Tim)
Limiting certain nutrients in a planted tank definitely has its place, not something I have gone into myself yet