I agree with the quote in this article - it is a struggle for many website owners to keep up to date with the latest versions and do any redevelopment work that it's needed as a result. However this isn't the result of WordPress moving too fast, it's a side-effect of the fact that WordPress websites are built by combining third party themes and plugins that aren't necessarily designed to work together. Clients love this because it reduces development costs, but don't realise the hidden cost that this brings in terms of ongoing maintenance. You can't blame WordPress, it's just the nature of this sort of website. WordPress professionals need to educate their clients about the issues so they can make informed decisions about how complex to make their website in the initial development process. If they don't have much budget for future maintenance, they need to keep things simple from the outset. We have spent a lot of time figuring out the best way to help our clients keep their websites up to date and fully tested, you might be interested to read my blog post 'How we’re helping all our clients to keep their websites regularly maintained'.