I'm a UX designer who has worked at large online brands for the last 15 years and I completely agree with this. For all the millions companies spend on "analytics", they have no ability to measure the effect of any given design intervention over anything more than the duration of a test. So they don't care - because they can't.

As a designer, you have to accept that. If a design you know customers hate has shown a positive effect for the business (and no, they don't re-test these things - it's first past the post my friends), then that design is there to stay. You can try your best to persuade everyone otherwise, but only the law courts can save you.

This, along with the usually quite early realisation that the people you work for couldn't tell a good design if it exploded in their custard, is probably about the worst thing about working as a designer in a commercial context. Just about.