This is management not AP specific and was written before the R600 was on sale, that aside... from the Zone Director online help guide:
The maximum number of WLANs configurable per ZoneDirector controller are as follows:
On single and dual-band 802.11n APs, the maximum number of service WLANs deployable per AP radio is 27. These APs support maximum 32 SSIDs per radio, but five are reserved (two mesh SSIDs and one each for monitor, recovery and scan).
802.11ac APs support up to 27 service WLANs on the 2.4 GHz radio and 13 service WLANs on the 5 GHz radio.
CAUTION! Deploying a large number of WLANs per AP will have a performance impact. Ruckus Wireless recommends deploying no more than eight WLANs per AP radio.
Each WLAN SSID broadcast takes airtime and reduces the response/efficiency of the APs. It is a real effect. Lots of SSIDs will degrade your wifi network. If I can find the earlier thread on this will post.
The ability to create numerous SSIDs above a practical limit could be for situations where they are switched on and off by schedule.