Although SEO copywriters probably do not use exclamation marks as much as those involved in more informal kinds of online writing, this is one type of punctuation which is becoming much more common thanks to the Web and other current forms of technology employing text. Emails and text messages, forum posts and online comments are typically crammed full of exclamation marks, sometimes as many as three or four at a time.
There has been speculation about the rise in popularity of what was once used sparingly. In the past, exclamation marks often appeared over-enthusiastic, maybe a bit forced and loud, and possibly lacking in taste. Their tendency to over-emphasise could come across as slightly desperate in tone. Now, the thinking is that text on a screen automatically looks less emotional and more subdued, so writers are compensating by scattering exclamation marks liberally throughout. As this has now become what is normal, those who write with more restrained punctuation risk appearing cold in comparison.
Another theory is that exclamation marks could imply uncertainty and a lack of confidence on the part of the writer. Being unsure when typing a simple statement about its likely effect on the reader, an exclamation mark is added at the end to prop it up and signify assertion. Some people think that the overuse of exclamation marks has come about because of peer pressure to appear active and excited all the time when online. Whatever the truth is, the best UK copywriters have their exclamation marks fully under control.