They cause health problems on the level comparable to smoking or bad sleep.
I get that sitting an excessive amount of the day, or wearing shoes for all your waking hours, can be bad. Is that all you mean or is there something more?
https://www.scientificamerican.com/article/going-barefoot-is...
The biomechanical differences between barefoot and shod distance running: a systematic review and preliminary meta-analysis https://pubmed.ncbi.nlm.nih.gov/23996137/
Studies show being barefoot makes you smarter! https://www.yourmodernfamily.com/barefoot-kids/
https://breakingmuscle.com/fitness/the-pros-and-cons-of-bare...
As for sitting, there are countless studies showing it's bad for health, posture, even causing hemorrhoids. Just search for 'sitting harmful'. There's a lot more consensus on this than barefoot vs shod.
For running, you have to unlearn the heel strike type of stride that most people adopt when they use cushioned running shoes. You need to roll your feet as you land, just as if you were running barefoot.
I don't run much, but for walking I've preferred solid soles made from high durometer rubber for a while now, because they beat up my feet a lot less than a pair of cushioned sneakers for long walks, and it's a lot better than going barefoot in -5C weather :-)
My dad wore clogs for most of his working life. Not the old-fashioned carved wooden ones, but the type with leather uppers and a glued on anti-slip layer of rubber on thick wooden soles. He said they were the most comfortable working shoes for varied surfaces and uneven ground.
I use minimalist shoes, not true barefoot running. For pragmatic reasons. Broken glass, dog shit, rusty nails. Also, even nudists put a towel under them when they sit at a cafe because they care about basic hygiene. I don't want to leave my skin and sweat on floor. You need a very thin, flexible and uniformly flat sole. Isolation is not important for running because your feet are mostly in the air and exercise warms up the muscles. You may want to put on an extra pair of socks for walking in winter. Rain and mud are a bigger problem and I keep a backup pair of standard shoes for that. Cycling also doesn't benefit from barefoot so I use normal shoes.
A common argument I hear is that barefoot might work on dirt and soil. This is not true actually. It takes me less effort to run on pavement and sidewalk, because I quickly adapt to the steady surface and focus on other aspects. On a trail I need to constantly adapt to changes in slope.
The key change I noticed is that I no longer get ankle or foot pain after a long walk. I now need literally a couple of hours of walking for my knees to get sore.