"The researchers looked at samples from a big number of mountain landscapes [...], comparing their rock types and climate conditions. They found that once mountains pass a specific height, the channels [they mean the area between mountain peaks/ridgelines, basically the path e.g. a glacier "rides" on] become very sensitive to even the smallest changes in their steepness, and that limits the heights of the mountains around them. After adding more data from hundreds of mountain ranges, they could confirm this pattern, that mountain height is limited once its channel's steepness crosses a certain value."

Not sure if I understood "mountain channel" correctly, I don't know much about geology, please correct me if I'm wrong.

EDIT: Think I got "channel" correct though, there's e.g. the English Channel, if you imagine it without water, England and France could be seen like mountains.