Reading this thread got me thinking back on my own experiences with novice gamers. I have often seen this same tendency to make things way more complicated than they need to be, and that has brought me to a revelation.
We're apt to think of "prefab" statblocks (where attack bonus, damage values, and so forth are all pre-calculated and presented in their final form) as ideal for newbie players and DMs. Veteran gamers want the complicated details of how all that stuff is computed; newbies need to be shielded from the nitty gritty.
But this is exactly backward! Newbies are the ones who need to have the process explained in detail. They need to be able to see where the numbers are coming from. We veterans, on the other hand, can look at a statblock that says "Longsword: +7 to hit, 1d8+4 damage," scan down to the ability scores for Strength 16 and the equipment list for a +1 longsword, and break it down into "+3 Strength mod, +1 enhancement, +3 proficiency bonus." For us, it's convenient to have everything presented in a minimalist form. Give us the final numbers, and we'll reverse-engineer the details on the rare occasions that we need them. The rest of the time, we'll just roll to hit and damage and carry on.
I suspect the main reason we get it wrong is impatience on the part of veterans. We watch a new player carefully check which stat to use for an attack, add that stat mod to the d20 roll and then pause to look up his proficiency bonus, and then do it all over again for the second attack, and wish he'd just tot up his total attack bonus, write it in big numbers on his character sheet like everyone else does, and quit wasting everyone's time. What we have to remember is that the newbie is learning as well as playing. Reading the rules is no substitute for using them at the table. Once the newbie gets a handle on how everything fits together, he can start taking shortcuts.