Eating a balanced diet is very difficult these days.

I'd like to see the evidence of the harmful use of supplements.
Surely the extreme dosing and typical high dose use by body builders, does cause concern. But for the doses suggested here, which are very moderate, that is another thing entirely.

Many people today use acid blocking drugs chronically and this alone creates a malabsorption issue with deriving benefit from the nutrients in foods. Removing acid from the stomach impairs
Calcium, magnesium, iron, zinc, B12, folate and some trace minerals like copper and chromium.

Many people therefore are suffering from hidden low values of B12, folate, magnesium, and Vit D as well. Studies show many do not receive the RDA in magnesium alone, in fact.

Also 10-30% of people have the DNA mutation for methylation systems, which are called MTHFR. This means they need a special B12 and folate (methylcobalamin and methylfolate) in order to make neurotransmitters as well as metabolize food properly, and make normal blood cells. People with this DNA error may just starve in the midst of plenty.

People may be gluten intolerant and have inflamed GI linings and not absorb food nutrients properly. Crohn's disease also
is well known for causing many nutrient deficiencies.

So being the diverse population that we are, we cannot really trust blanket statements like some are making here against using supplements.

People can get tested for many nutrients today. Vit D, B12, B1, and B6 can be tested for, from your doctor.