The entire section is a deception. The real reason is to strong arm everyone into a subscription model where you never own the software that runs on your computer. That's the real end game, not this nonsense about how easy it is to launch an application if its a URL in a browser.
It's really future OS updates that threaten that.
There have been no major advancements in PhotoShop for my needs that really warrant an upgrade. No added value. I paid for CS6 long ago, and it should run properly without artificial disruptions indefinitely, because that is how it was marketed to me.
I also believe them when they say performance was an issue that kept them from doing this until now: the fact that the Photopea guy can do a large subset of Photoshop's functionality in the browser is astonishing, but power users expect a lot more, and wouldn't pay Adobe's organizational licensing fees for anything less.
Yes, this will allow them to enforce their subscription model more tightly, and likely push all kinds of new monetization at users. You're right about that part, I just don't think it's the only reason.
Indeed, the convenience argument is just a pretext. They long to see the back of the days when you could buy Photoshop 7.0 for a one off fee and still use it today.
But as to organisations, if it is that bad, it sounds more like an exacting support contract or overly bureaucratic processes. (Or how things are in the public sector.) In either case, if the company makes the process of getting its work done needlessly tedious, then it deserves to founder and give way to the agile competition.
It is really unfortunate if this is a main reason that webapps are so popular with all their bloat, wastage and transience.