The same quantity as. As with as many (def. 2), the meaning of much as a large amount here is qualified by what follows. For example, Please help yourself to as much of the meant as you want indicates whatever amount you wish.
[ Late 1100s
however much, much as. Even though, no matter how much, as in As much as I hate to, I must stay home tonight, or However much it hurts, you ought to admit you were wrong, or Much as Karen would love to see us, she can't get out of her prior commitment.
[ Late 1500s
so much as. In effect, nearly the same as, as in Mom as much as told Jane she couldn't go, or The clerk so much as accused the customer of shoplifting. These expressions intensify the meaning of the verb and indicate that the action is unexpected.
[ Late 1300s