I give an incredibly similar warning every time a company I'm working for starts trying to dip their toe into A/B testing. I have a lot of experience with it at scale (one at a fortune 100 company) and I've even built an a la carte testing framework in aws for a company that didn't like Target or Optimizely.
Every single time I warn them about how the bill of goods they've been sold with A/B testing is almost completely unattainable, especially in the way that they want to go about it. They won't magically start getting more conversions by changing a button color. Even if they start getting more clicks, they rarely start getting more complete conversions, because the increased numbers is usually from people who weren't good leads in the first place.
On top of that every company I've worked with has no idea what the real methodology for good tests is, no matter how many times I explain it or put it in a slide deck. I would constantly get requests to use A/B testing for feature rollout.
Them: "Hey, could you do an A/B test of our existing site design and our upcoming redesign?"
Me: "if the old design performs better are you going to toss out the redesign?"
Them: "No we're going with the redesign but we want metrics on how it'll affect traffic"
Me: "Those metrics are useless if you aren't going to listen to them, and if the results come back and the old design performs better, you're not even going to put it in a presentation because it's counter to your planned actions. There's literally no point in running this test"
Them: "Run it anyway"