CRAB: To do with PPruNe's (or Internet Brands) vBulletin forum software options (and which is common among other types of forum software).
For example if you write pprune all in small caps the software will automatically change it to what you have just read. Other 'household' names such as social networking sites beginning with the word 'Face' will be automatically overwritten and somewhere along the line someone somewhere felt that the word laser required a permanent '@' symbol .. but not the word 'lasered'!
All to do with the 'commercial considerations' of the site I suspect and was also the reason why until last year you couldn't post email address although now, thankfully, that has changed.