[johnklos]

For all the redundancies that exist, "cloud" isn't reliable and therefore can't replace the mainframe. Then again, most things don't need mainframe level reliability, which is why Microsoft Teams (and other Microsoft services) is problematic today.

[kmoser]

It's not just a matter of reliability: mainframes allow tighter coupling between different parts of your application, thus faster performance, since everything is (or can be) essentially on the same hardware that is optimized for data processing. Cloud services are getting closer to bridging the gap, but for some applications mainframes will still be the only way to go. One main advantage that cloud has is you can distribute things into services that can be hosted anywhere: the same cloud service, a different cloud service, etc. Yes, you can do that with mainframes, too, but in the past mainframe software wasn't written with that flexibility. Today, everything is all about distributed microservices.

As to the article's premise that people are getting locked into cloud services as they used to get locked into mainframe services, you could make the same argument about any tech: write your app with language X, and you'll have a hard time translating it to language Y. Write a low-level app that runs on Intel chips and you'll have a hard time porting it to Motorola. That's the nature of software development.