"Improving your UI is a waste of time"
"UI is pointless"
What the author is actually saying (imo): "UI redesigns create costs that should warrant them. There are a lot of times when a website makes radical redesigns for comparatively marginal improvements. These improvements are not always worth it for reasons like existing userbase having to relearn the new ui."
This is a fair point and I think a lot of times places rebrand because they want to look like they're doing something even if it comes at the cost of overall usability.