True. But when you're new to vaping it can take a while until you kind of find out what your vaping habits are like -- how often you vape, what you like to vape, how strong you like to vape, how much throat hit you like, etc. From my point of view I think it helps to start in neutral territory/middle of the road and adjust up or down as your personal tastes and needs develop -- and as you figure out where your nic tolerance lies most importantly. I started at 18, found the TH wasn't sufficient for me (for the hardware I was using at the time), upped it to 24mg and was quite satisfied there for a while, at least until I upgraded my PV and attachments and my body started getting those nic overdose symptoms from the extra vapor I was getting and I had to cut down to 12mg.
Either way you go though there's almost certainly going to be tweaking you'll have to do, whether it's hardware or juice, until you find your sweet spot. Starting in the middle I think just makes the distance you need to travel potentially a little shorter in either direction.