You're right, on looking back at the threads it was not nearly that hot. But it was elevated enough to cause issues. People reporting their laptops got uncomfortably hot, compared to stock.

Looks like the actual point where you start to get problems is quite low, somewhere around ~38C, so if the mod elevated temperatures even to 40-50C, you'd be in heavy discomfort or possible burn territory. This paper talks about skin lesions and burns happening around there: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3853603/