Many of us simmers , especially with airliners, do effectively do a mediocre weight and balance , if only to get the fmc to work properly.
However in smaller a/c it is more important as many of the smaller a/c have little power to spare. but how many of us bother?
Virtually every small aircraft produced cannot carry full fuel plus a full compliment of seats , there are some exceptions but they prove the rule,
Take the latest cherokee 180 from A2A if you look in the fuel tank you will see a tab you should not fill the tank above that tab if carrying 4 people, a simple security aid.
Howev