Weird thing is that I don't actually have a connection to five sachets of sugar. People might frequently handle one or two sachets at a time and can conceive of the idea that five isn't that much heavier but at that point we might as well write "... and weighs as little as 20 grams, or roughly five sachets of sugar"
Ah that's something I didn't even consider - and I guess a lot of people don't even consume things that we normally add individual sachets of sugar to. At least giving the weight in grams gives you something to go by.
Ultimately it's not a huge deal, it is still a little odd though!