It's very helpful to have some guidelines such as "add salt", totally creative cooking would allow me to say "Hmmmmm, maybe I'll try sugar instead, or possibly bourbon".
Way too much of a range of possible flavor outcomes and you never know until it's finished and the meat is ruined whether no one wants to eat it or not.
I agree recipes should only be used as a template with variations added in or taken away but the general guidelines help assure you're not throwing away a 3lb roast because you added jelly as a glaze and not worcestershire sauce (why does that name have to be so long and damn near unpronouncable?)(have you ever seen what it's made of? You might not eat it again, it starts with 3yr old fermented fish).