DSP is no joke. I have it in my RV for radically improved sound quality for those long drives. All future cars and trucks of mine will be DSP equipped.
DSP may be used very differently in an open boat versus a closed vehicle cabin. However, DSP can be just as valuable in a boat as in a vehicle. Imagine phase correction on multi-pair tower speakers that are staggered on a forward leaning tower or staggered mounting on front and rear tower tubes. Or, DSP can correct the phase between the tower speakers and subwoofer at a focal point just behind the transom.
Earmark Marine and Earmark Car Audio does a ton of DSP. And Wetsounds added DSP to their newest demo boat.
The one cautionary note is that there are many, many complexities related to phase correction other than the distance differential between drivers alone. And there is much more to equalization beyond simply creating a ruler flat response. It's still a job best left to the pros. But there is no doubt that DSP is a game changer.