The learning state is not really useful, even with STP;-)
Basically, RSTP was built on the top of STP. If the RSTP enhancements are not applicable to a particular scenario, RSTP just behave like STP.
So for example, on a port with no neighbor and not identified as edge, the transition to forwarding will be slow, exactly as in STP (and you'll have a learning stage). Also, if an RSTP port is connected to an STP port, there will also be slow transition using the learning stage.
It's true however that in a network adapted to RSTP (p2p links, all devices running RSTP and edge ports identified), the learning state should not be used.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...