And this article goes into quite detailed reasoning as to exactly why baby headbands can be really quite dangerous. No bullshit or opinions on aesthetics, just facts.
https://www.byregion.net/cgibin/users/articles_viewer.pl?id=4668
This part in particular, explains it well:
"Placing a beanie hat or headband on a baby may be a modern style choice that has the same consequences. However, today we can see the later issues that can develop from pressure applied to the developing brain.
To move the bones in an adult skull requires 5 grams of pressure, which is the weight of a nickel. To move the bones in an infant’s skull requires less than one gram of pressure. Premature infants require a small fraction of a gram.
The weight of an infant’s head on a soft surface is enough to change the shape of the skull and the position of the bones. This is why children suffering from torticollis or tightness around the dural tube which prevents movement of their head from side to side will cause the head to become flat.
Today doctors prefer to avoid forceps and vacuum deliveries because the pressure they create can cause many problems from misshapen head to brain damage and an assortment of symptoms of developmental issues and developmental delay in between.
Many people will argue the headbands and beanies are not tight. No, to an adult they seem soft and stretchy but to a delicate infant they apply considerable pressure. Everything is relative. Adults may pick up a 10 lb weight and it is nothing, but would you expect the baby to be able to pick up 10 lbs? No. The baby will only be able to lift a few ounces. But the adult does not expect the child to lift the weight so why do they expect the child to bear the excessive pressure that to an adult is no pressure at all? It is the same difference.
To stay on, beanies and headbands must exert more than one gram of pressure, therefore it is effecting brain development. If there is a red mark on the skin, too much pressure has been exerted. How long does it take for that red mark to go away? That is an indication of how tight that felt to the baby. If there is an indentation on the head, it was much too tight and the baby probably developed a headache from the experience but was unable to complain in adult language and people just say they are being fussy.
Not all children will show overt signs of skull compression while in others the results can be severe. Much will depend on how often pressure is applied and for what period of time it is applied. It will also depend on if there are other imbalances in the body such as tightness in the dural tube, misalignment of the spine, imbalance of the pelvis or any other restriction which has caused the body to be out of balance. The compression will affect the weakest areas of the skull, the areas where the bones may not be in quite the proper position or where the suture is not the strongest or where the pressure is uneven because of other imbalances. The bones may either be moved out of position or compressed to the point where they overlap and apply even more pressure on the brain. This can cause huge problems for the developing child."