Either you concretely agree on the finances or you don't. If you don't have any explicit understanding/agreement, the vast majority of relationships are going to have problems. Having separate accounts forces you to come to an explicit consensus
Your response implies that its unhealthy to speak openly and clearly about finances. It's much healthier to be concrete and open about how money is managed rather than having some vague understanding or not talking about it at all. If you have a clear understanding that you've both agreed on, then a joint account doesn't provide any benefit.
Just because you do something doesn't mean you agree with it.