Everything you are describing applies to VPS systems.
There are differences, but those have more to do with optimal use of resources, and in that aspect managing cloud systems is actually more complicated. At least the behavior of your own physical systems is consistent and predictable.
Besides touching physical machines, what is it you think a sysadmin for cloud systems doesn't do?
How often do you need to monitor your EC2 instance for failed physical disks or bad sticks of memory... never :)
Additionally, it depends on how much you outsource to your cloud hosting provider. Many people trust ELB to do the right thing. It is a pretty reasonable product, but having used keepalived + the default builtin LVS[2] that is in every distro kernel out there for more than 10 years, why trust Amazon to do it better? Why use Amazon Dynamodb when there is Riak[3] or Amazon Elastic Cache when groupcache[4] is so awesome?
Using cloud services == outsourcing some/all of the traditional sysadmin work. Many people who consider themselves devops people are smart developers with very little real sysadmin experience. Please don't fall into the trap of considering them exactly the same. It is an interesting hybrid role, but is distinctly different.
[1] http://en.wikipedia.org/wiki/OSI_model
Yes, but that doesn't mean that any particular instance of having to learn new tech is something ve should celebrate. The opportunity cost of learning this might be that ve doesn't learn something else useful.
I've professionally managed thousands of RHEL/CentOS/Fedora/Gentoo/Ubuntu/Debian servers in production (and that is just linux!) and not had any real issues learning the variations. Sure you learn different package managers, /etc/sysconfig vs /etc/default, different init scripts, but it is just semantics. That is why sysadmins get paid, to be experts that know the differences.
It is a good thing to know both, embrace the new tech.
EDIT: Oh and I gave you an upvote, this isn't mean to be a snark.