Myth check: Should I only use one product line for facial care?

A beauty myth that has persisted for years is that facial care products all have to be from the same brand, otherwise they won't work. Is that true or is it more of a marketing strategy for the cosmetics industry? After all, it looks nice when all the care products in the bathroom are visually coordinated.

I confess, I use different skin care products. I don't wear the same clothes every day or eat the same food every day. Then why should I “do” this to my skin? The skin is different every day, reacts to temperatures, environmental influences, hormonal fluctuations... accordingly, daily care should be individually adapted to the skin's mood.
I also often have the problem that my skin, for example, likes a brand's micellar water, but turns to redness, itching or pimples when I use the right cream from the brand. That can hardly be the point of the matter.

For well-functioning and effective skin care, you don't have to use all products from the same brand. If your skin can handle it best, this is of course the care routine of your choice, but if not, then just add variety to your skin's everyday routine.
That doesn't mean that you're constantly trying out new products, using a different cream every day, etc. But your serum from company X certainly doesn't stop working just because you then apply a cream from company Y. It is much more important that you use the products in the right order and that the ingredients are well matched to each other and, above all, to your individual skin type.

Only if you use prescription care products for skin diseases should you not be so keen on combining them and stick to the instructions given by your dermatologist and/or pharmacist.