Cisco – Why does the ASA 5512-X not support traffic shaping

The cisco documentation claims that the ASA 5512-X does not support traffic shaping because it is a multi processor device. Why is this?

Is shaping just inherently active?

It seems like the shapper is a good feature, i don't understand why it is not available.

To add more details, the shape command is not available under the class default policy, it is located elsewhere?
Here is what I normally apply

class-map RTP-traffic
 match dscp ef 
class-map SIP-traffic
 match dscp af31 

policy-map voice-policy
 class RTP-traffic
  priority
 class SIP-traffic
  priority

policy-map outside-policy
 class class-default
  shape average 5000000
  service-policy voice-policy

service-policy outside-policy interface outside

But when I go to apply this i only see

ASAX(config-pmap-c)# policy-map outside-policy
ASAX(config-pmap)#  class class-default
ASAX(config-pmap-c)# ?

MPF policy-map class configuration commands:
  exit             Exit from MPF class action configuration mode
  help             Help for MPF policy-map class/match submode commands
  no               Negate or set default values of a command
  police           Rate limit traffic for this class
  priority         Strict scheduling priority for this class
  quit             Exit from MPF class action configuration mode
  set              Set connection values
  user-statistics  configure user statistics for identity firewall
  <cr>
  csc              Content Security and Control service module
  flow-export      Configure filters for NetFlow events
  inspect          Protocol inspection services
  ips              Intrusion prevention services

And the shape is not available.