We made very good experiences with a realtor when we bought our apartment. Where I live, there is a lot of bureaucracy at play and the process is not easy to understand even when you have experts to ask. There have also been very sophisticated frauds on both sides - sellers and buyers - that a realtor from a well-known franchise blocks.

Generally, I see no problem with competent middle men. They offer a service like any other service. If you want the service, you buy it, and if you don't want it you don't.