In Western societies, Financing has become a way of life. The basic form of financing is to buy a certian product or service (e.g. TV set,Car, clothings, ...etc.) and pay in installments and interest.
Loans in the prevalent economic system involves interest, which is prohibited in Islam.
Aside from that, loans often encourage consumerism, where people buy things they don't need with money they do not have!
You can read an article on personal financing on the Islamic Halal Finance site.