[indrora]

It's for having in your dev environment and/or sometimes as a toggle for "Special Requests" -- if your session is authenticated and you're marked as blessed, you get extra information about what the application is doing under the hood so you can see what's going on in production as well.

Some let you add whatever information you want into the panel.

It's a convenience feature to make it easier to wade through information rather than having to dredge everything out of logs by hand, which a lot of people still do.