Harry I was going to reply back when I saw this that 99% of the time I also use a drill press when I use a Forstner. A few times I've used them freehand, for drilling plug holes I think. However, getting them started without the bit skating around on the surface, especially the larger sizes, can be quite tricky. That jig is just another weapon in the arsenal to get jobs done. If someone needed to make a very accurate hole in a location where a drill press is impractical then they now have the idea for a quick and cost free jig that will get the job done for them.For that unusual job I fully agree, but when used in a drill press (what they intended to be used in) I have never found any difficulty drilling multiple holes vertically and in the correct spot.
I have one of these. Not the best but it did help me guide the bit.Off-hand, this is all I came up with without my coffee. I believe you could also make one somewhat similar, but out of wood.
I never buy sets of bits or the like. I prefer to just buy the one I want, then later buy whatever else I want, one at a time.