[threeseed]

I assume from this comment that you've never worked in the enterprise.

Because (a) major decisions like choosing a mainframe are not made by tech managers and (b) every company is built around vendor lock-in.

Who do you think companies like Atlassian, Oracle, Salesforce etc sell to ?

[paleotrope]

It's a little off to think that a mainframe was "chosen". Software and the companies that write it and support it "chose" the hardware for you.