I think there's a pretty good argument that "made for the purpose" doesn't always equate to "good" or even "safe." Although, I suppose there's some subjectivity in those terms - I may have different criteria than other people do.
Dunlop's product is basically mineral oil scented with a small percentage of lemon oil - as are most other fretboard oil or conditioner products. The lemon oil component evaporates in short order and doesn't really play any significant role, except that it does help break down grime as you apply it. The mineral oil will also help loosen grime, and will help the fretboard look shiny and new, but it doesn't offer any actual significant protection (in terms of keeping soil out of the fretboard, moisturizing it, or keeping moisture in the wood). Mineral oil doesn't catalyze or cure, it just sits in the wood until most of the oil on the surface has been worn off, and then the player decides to reapply it. But once it's on there, some of the oil will always remain in the wood. What this means is that if you ever need to do a repair that involves gluing or other significant modifications to the fretboard, you'll be cursing the day you decided to oil it.
So - if your goal is just to make the fretboard look nice, and you're not concerned about serious repairs, the dunlop product or other products made for "oiling" a fretboard will work great. They're certainly popular and sell easily. But my perspective - speaking as the guy who has to repair the fretboard when there's an issue years down the line - I really don't think these products are a good idea, since they make the work I'll be doing more complicated, and they don't really offer an upside other than a temporary improvement in appearance.
If your fretboard is dirty or grimy, the best thing I've found has been just really hot water on a dollar store microfiber cloth. If the grime is very stubborn, you can use a fine (white) 3M pad to help. Further, if you want to actually protect the fretboard, in terms of providing a protective finish to keep it from getting dirty and to provide a barrier to prevent it from drying out easily in low humidity, then the thing you want is an actual curing finish - something like
Stewmac's colortone fretboard finishing oil. Or even any other drying oil finish that can be applied thin. These finishes get applied once, you don't have to re-do it every 6 months. And, importantly, they actually offer permanent lasting protection. Fretboards with an actual finish on them will absorb and release moisture more slowly and will remain more stable in service. These finishes cure thin enough that the fretboard doesn't look finished, so for instance an ebony fretboard will still look like an ebony fretboard - it'll just retain it's as-new polished look instead of getting dull and uneven quickly. Because these finishes cure, they don't remain "wet" in the wood and don't interfere with repairs down the road. You can sand them, glue sticks to them, frets aren't bothered by them, and so on.
I'm sure there are people who will disagree with me, and who feel like fretboards should be oiled or "conditioned." And I know that the presence and popularity of products designed to do that seems to back that position. But I'm basing these comments on a few decades of building and repairing instruments - dealing with them when there are actual problems.
