Often I see a detailed guide on how to install something, in most cases, the commenting on the A, is good enough.
But, sometimes the how to needs to be tested on multiple systems (e.g. Ubuntu 12.04, 13.10). Therefore the comments section falls short, since the errors, and such needs to be posted, for multiple people to think about how to fix it, and to get a progress overview of the soon to be completed how to. Compiling, packages and such.