Oh man, when I read some views here, my facial expressions fall apart... And I'm just glad that I'm building my own house!
In my previous long-term relationship, each partner had their own financial obligations that only concerned them. In my case, an expensive hobby; in his case, a child to support and, of course, HIS house. That was the reason the finances remained separate.
We shared common things (shopping, costs for the shared children who then arrived, vacation), otherwise, each had their own money. I paid for my clothes, my hobby, my lunch at the canteen, and my car myself. At times, I also paid rent since we lived in his house (with reduced or no rent during child-related part-time work).
He, for example, put every cent into repaying his loan. And that would have affected everything that would have been "left over" for me if we had just pooled everything together. And at the latest at that point, I would have gone up in arms; it’s his house, we were not married... in the event of a separation, I would have been left empty-handed.
Anyone who, as a member here wrote, starts marriage with "nothing" can probably pool resources, but if everyone already has a history that also has financial consequences, you have to think differently and may come to a different solution.