Sole trader losses

Hello,
I'm still studying level 4 tax, but am helping a friend with their tax return. I've just looked at their last tax return and found that they made a profit of just under £8000 but their advisor at the time then took off £5000 loss from the previous year. This seems unnecessary to me, as they would have been under the tax threshold anyway wouldn't they? Does this mean they can't now bring that loss forward to use against future profits?
Thanks,
Shells