I think the problem with this article is its starting point: "Legacy systems tie you to unproductive legacy thinking and lead to stagnation."
There's a huge assumption that because it's old it's going to be disrupted by something better. But systems aren't just about technology: they're about people, both within your organisation and beyond it: customers and business partners. How many businesses are ready for their IT department to jeopardise those relationships?
Believing that legacy systems are the only way forward will of course lead to stagnation, but given that this forum is IT-focussed I don't think there will be too many Luddites here.
Disruption is already a cliché despite being thoroughly unproven in the enterprise. Certainly entrants have disrupted long-standing business models and those are easy to reel off. But how many businesses have successfully disrupted themselves to conquer new markets without losing existing customers? Amazon EC2 is all I can think of and it's not an easy model to emulate.
And more relevant to this article, how many existing businesses have done that by buying a new piece of software? Would the author care to offer any examples?