This is poor advice. Lots of people make a quick judgement on your trustworthiness based on whether you at least have adequate design. If they turn away in 200 ms because of poor design, they will never be able to evaluate what your true value proposition is. Many decisions in a B2B context are defensively made, so as to avoid the risk of looking stupid in the future if things don't work out. Like the old saying, nob…
For B2B products it's a little different. When you're holding an MVP in your hands, it's really hard to tell whether you're grasping a rusty old anchor that will drag you to your death, or whether you're looking at lightning in a bottle.
One quick way to tell is if businesses sign up and user it even though it's as fugly as can be.
If, when pitching the product to a potential sale, the subject indicates that they need particular cosmetic changes before higher-ups would approve it, then you're likely pitching a dud product.
If, otoh, they interrupt you during the pitch of that fugly product, and offer to trial it immediately, or buy the prototype, or call in a higher up, then you have the proverbial lightning in a bottle.
Cosmetics is, I think, a good indicator for B2B products - if people want it even though it's ugly, you're selling painkillers. If people want it only when it's pretty, you're selling vitamins.