These products have existed for decades (I know because I’ve used some of them), but it is not a solved problem. For all but the easiest cell cultures, growing cells without FBS is extremely tricky. I know that marketing materials (and some publications almost certainly by the manufacturer) say otherwise, but that’s marketing for you.

Not every type of cell or tissue has the same requirements, and things get difficult very quickly as soon as you deviate from the most common cultures. Tissues and non-cancerous (or in technical jargon: non-immortalized) cell lines are usually much, much, much more difficult.

And even if you manage to grow your cells, “serum-starving” will likely happen due to some unknown missing nutrient / factor, which will stress your cells and alter their phenotype. Even if they don’t lose their adherence, undergo apoptosis, or some pathologic autophagy, they may produce all sorts of extracellular vesicles.

FBS is really expensive, and quite mysterious. Nobody really knows what’s in there exactly. [1] Researchers would love to be able to stop using it, because it could mean more reproducible results, and at scale, fewer expenses. Unfortunately, FBS is also unreasonably effective, so we continue to use it still.

[1] This is only a slight exaggeration, but it’s approximately true. Trust me, I know this sounds like a preposterous claim. But this is an absolutely-insane rabbit hole where a lot more research is very-needed. A full characterization of FBS and its effects on cells does not exist, and is much more complex than it probably sounds.