More reasons that I can count. It can help, a lot.
1. Often on cascading delays its due to a late inbound arrival of aircraft vs a variable such as maintenance, etc. A cascading delay due to inbound delayed aircraft allows one to track the inbound aircraft to know what time its actually due to arrive, especially as the delay is usually occurring as the aircraft has not left its outbound terminal yet. This can translate to spending many less hours at the airport. Happened to me recently at NRT, was waiting for an inbound and my flight kept getting delayed in 1 hour blocks. Knowing the delay was because the aircraft was being delayed in SIN, I just kept my eye on it and stayed at my hotel. This ALSO means you can get a jumpstart on rebooking options ahead of other pax should you now be misconnecting.
2. If the delay is due to mechanical, its less easy to track but at least we know the aircraft is physically on the ground.
3. If its due to something like crew sickness, pilot not avail, etc, then again, we know its unrelated to aircraft so probably best to stick around.
4. Suppose the delay were due to something more serious like a diversion of the previous days aircraft, etc? That would be grounds to again get ahead of rebooking options.

To name a few.