There are alot of benefits to running a fuge but it's not mandated that you have to. I personally like fuges bit they have to be at least half the size as the Dt if you want to see significant changes IMO.
You can have significant changes with much smaller fuges.
I have a 5-10 gallon section for macro and I have virtually eliminated nuisance algae in my DT.
I also run phosban with carbon and I rinse all frozen meaty foods.
well the benefits of having a refugium is that the mico creatures living in the display tank that most of the time be eating by your inhabitants well have a chance to reproduce in your refugium...