It works, but just for _some_ solutions. For instance, there are multiple providers of support for PostgreSQL. And there are many companies offering support/consulting for WordPress.
IBM RedHat is the steward of RHEL, and Canonical is of Ubuntu, so if you want support from them there are no real other options, but they do work with multiple different ISVs.
If you want to stay 'independent' and have the most leverage you can take a linux which is not from a bigco, such as Debian.
I'm really worried about cloud-lock-in for bigger companies. My previous company switched large amounts of product to AWS, when I asked about how this was feasible after doing back-of-the-envelope calculations they said: well you should not consider list price, nobody is paying list price, we get discounts.
This reminded me of an ISP I worked for in 2006 that invested in large amounts of Solaris machines because they got big discounts instead of going for the much more obvious Linux route. Then after two years or so the new (Oracle at that time?? I'm not sure) sales rep paid a visit and they said, when they were not able to sell MORE new servers: OK screw the discounts, from now you're paying list price. So that got them stuck in a real bad place. I'm afraid the same might happen to companies who move to cloud providers as well.
And then I've not even touched on issues such as privacy, security, business continuity, and losing the skill to actually run your own hardware
