Late reply, I'm rarely on here but I wanted to answer you and anyone coming along in the future. US here, talking about conditioner we use to make our hair soft and shiny after using shampoo.

It's happened a few times, no doubt with different products. The reddit thread was saying it's because the conditioner residue dries the skin and you should wash off with soap. Funny enough, I just did this yesterday, for the first time in many months. No problem so far!