I expect you would. Civil procedure isn't (for the most part) particularly complicated.
But there's no way the average person is going to just *know* how to apply for directions, how to draft a witness statement, how to complete a claim form so that they can claim interest, which court they should be applying to, which statutes apply (and where to find them and to check they're in force still etc), what defences the other side may use etc etc. You're right - none of these things are particularly hard to find out (indeed courts tend to bend over backwards to help litigants in person) but add them all together and it's going to take someone who isn't legally trained far, far longer to put a case together than someone who is.
And the LiP screws it up, the ramifications can be huge.
Paying a good lawyer for an hour's work will save a LiP at least 10x that, as well as all the associated stress, worry and confusion.
And, just as importantly, they've got someone to sue if the case gets ballsed up ;-)