Yes, I used to use one, a cheap one - which wasn't a high cranking one, but had 17ah which was enough to run a bait well.
However, since moving to a semi-traction battery (Varta LFD75 Varta Professional DC Leisure Battery 75Ah) I haven't bothered as this will run the boat, radio, sounds, twin plotters, blah blah all day no issues. And when it has had issues (low water in a cell) i just pull started the engine - as being only a 50hp it has the ability to.
The most i used the jumper starter for is other peoples cars, one was on the slipway and I helped him so he wasn't blocking half the slip when i would be coming back in!
For some of the bigger boats with shore power i can see the benefit of keeping a suitcase generator onboard:
R