The point was that relying on marketing messages causes the user having to research themselves what the product is actually good at and what it isn't good at an

The point was that relying on marketing messages causes the user having to research themselves what the product is actually good at and what it isn't good at and wasting time because the company isn't upfront the products strengths and weaknesses. The product might be sufficient in the end, but marketing will very rarely tell you what the product is actually sufficient at and what it is not. The statement wasn't about whether the product is actually good or not, though in extreme cases, yes, the product is worthless while the marketing is all rainbows and sunshine. But relying on marketing is bad for the user in nearly every case, even if the product is good. And even if you are "one of the good guys", your users won't know that. That's why you should verify from independent sources, or do your own research. If marketing was really a reliable source of information, reviews, samples, product trials etc. wouldn't be a thing.