People should treat emphasis as a limited resource. If we use too many exclamation points, too many italics, too many bold letters, too many underlines, too many colored fonts, too many... of whatever horrors people invent... it just makes readers turn off their attention and skip the emphasised parts, because there was so many of them.

The fact that the writer did not realize this is low-status, and in extreme cases could be even evidence for mental imbalance. (Here is a web page of some crazy cult, as a specific example.)