ACL is a superset of traditional, therefore you can't have both, (because the traditional are part of ACL).
1st let us try it.
#> chmod ug-w aab
#> setfacl -m u:me:w aab
#> getfacl aab
# file: aab
# owner: me
# group: me
So why is the ACL of user:me ineffective.
To explain this we can look at traditional permissions.
If we have a file as listed here
-r---w---- 1 me me 0 Feb 21 09:41 abc
Then I can read it, but I can not write to it. Why is this.
The OS first tries to match me to the owner, then the group, then to other. It matches me to owner. It then applies these permissions. It does not then merge my group permissions.
With ACLs the extra permissions are all part of the group permission, so will not be use for the owner.
I think ACLs are parsed in the same way: find what user group you are in, then apply this permission. (No permission merging).
If the users differ
If we did
#> setfacl -m u:anotherUser:w aab, then you permission will apply, as this permission is found first (for this user), and it is applied.