How to run nested xargs commands?

xargs is unnecessary, something similar to this will do the job without any piping or xargs:

sites=$(wp site list --field=url)
for site in $sites
do
  users=$(wp user list --url="$site" --role=subscriber)
  for user in $users
  do
    wp user delete $user --url="$site" --reassign=4
  end
end