Of course you could say the same about Edison or Maxwell, but that's roughly the right magnitude. Hating on Stallman as a person is not very elegant, hating him for the wrong reasons (at a glance, I spot: jealousy, misunderstanding, claims of irrelevancy and so on) is not productive either.
If you're going to criticize criticize the particulars of the linked article rather than the man. Thanks.
On topic: In case you didn't get it: the article (rightly) identifies software-as-a-service as a threat to open source, it allows companies that in the past would have shipped binaries and would have been compelled by the GPL to release their sources to do an end-run around all this so they can charge you for their software without ever having to release anything. That's a valid point and plenty of examples exist in the world today.
How serious this is is not for me to say but I do note an ever increasing trend towards lock-in and a more asymmetric internet which seems to draw a line between the 'haves' (the owners of infrastructure and services) and the 'have nots' (the users, smaller businesses). Ever larger chunks of a business operation are running on hardware and software even the business owners have no control over, stuff they couldn't keep alive even if their business depended on it. This sort of inter-dependency is exactly what we should be trying to avoid because it means that you are simply no longer in control, either because you don't have access to all the code that powers your business or because your code is only a minor extension to a bunch of black box code that you can not review or inspect on a machine that might be running all kinds of nefarious stuff besides what you think it is doing and that might come back to bite you one day.