People get offended by unsolicited advice all the time. Regardless of your intentions, that's how some people will perceive it. It's worse if they know you haven't used their product, because that makes you seem like you're flippantly handing out advice. You're likely giving off the impression that you think you're right without any experience or consideration of their product.

None of that actually discredits your suggestions though; you could be right.

As a counter example, some people are PoC||GTFO types who wouldn't take offense easily but would rather punch holes in your argument. Seems like you might be jumping in with the advice before you know if it's that kind of environment.