Thanks for the recommendation, I checked out the book (I had never heard of it) and it does sound interesting, by chance have you listened to the audiobook? It’s read by Wesley and I haven’t listened to any audiobooks read by him. (https://www.audible.com.au/pd/Masters-of-Doom-Audiobook/B00F...)
One example of that I've seen have spent significant time on tools like cloudformation can only (as far as I know) be used on AWS. Another would be where when you need decent storage performance - we have several cases where we use 20-40K IOP/s quite easily and doing that kind of work on the current cloud offerings is very expensive and usually involves significantly increase complexity if say you need this in your database layer as you suddenly have the need to scale horizontally while maintaining consistency and durability which is difficult. We can provision 6TB of networked 1M 4K random read IOP/s storage in a highly redundant, load balanced form that's easy to upgrade and scale for less than $500/month and it has little to no management overhead. Now while this may not be what your average startup requires it opens up a world of opportunity to how and what you do with your data.
Edit: I should note that we do, where appropriate use 'cloud' services including Rackspace, AWS and Azure where appropriate. Azure has had significant performance issues and has a lot of provable downtime especially due to internal network routing and DNS problems that they fail to acknowledge and we've found their support to be a joke if you know what you need / are doing, even their own O365 service has weekly outages that can take several minutes to resolve. Rackspace's support has been good but they do have a lot of small outages again often network related. AWS' has been alright be very costly unless you're doing either very small deployments or at the other end of the scale massive, horizontally scalable deployments, however their storage performance is woeful. For our mission critical or high performance deployments using our internally hosted platform is significantly fast and almost always cheaper. Our uptime across the platform is fantastic and it generally 'just works' while we watch our cloud hosted services suffer from inconsistent performance and service 'blips'.
If you host your own servers or even PaaS wherever, and you don't have an API and automation framework then yes - you will see benefits from having those things provided to you. If you already have these things and you're not spending a lot of time to make sure they continue to exist then you have a lot more freedom than locking into the tools that your 'cloud' provider has given you.
Some times people do, often they don't. We learnt that dealing with 3rd party vendors is a very time consuming and costly ordeal, especially when you realise that they don't care about your business, only about your money.
Not alone there, Microsoft is especially expensive for what you actually get but the more common players such as AWS and Rackspace are highly cost ineffective in many situations. I really wish people would stop calling it 'the cloud' and call it what it is 'outsourced hardware'.
I see this as a good sign (other than for those laid off of course), Twitter is fantastic but they don't need half as many people as they currently employ for their product. As companies get larger their agility and ability to change decreases. What's important is if they're laying off the right people.