Why would I use a unique_lock<> wrapper?

Why would I use a unique_lock<> wrapper?

I sometimes see code like this

std::unique_lock<std::mutex> lock(m_active_sessions_guard); // lock() the associated mutex
m_active_sessions[request_id] = session;
lock.unlock();

where a unique_lock<> is created just to lock the associated mutex.

Having searched, I've found that this class is not copyable. Is this the only benefit of using it?