[…] but most people who identify as LGBT in the UK will already be aware of the nature of certain states.
As I understand it, giving travellers themselves wholly new information is only part of the pupose of those advisories. They also create a record of officially recognized issues that you can refer to when dealing with third parties. That can come in handy if you have to explain your reservations about going or your need for special precautions to your boss or whomever. In more drastic cases they also allow you to cancel booked trips.