As opposed to people engaging in rampant speculation to guess when the next Direct will be, as it is almost all year long every year.
"When will we get to see the next Direct?"
The difference between the two is that people have come to expect directs at certain times of the year. When that direct never comes, we get people claiming, "Nintendo has abandoned the Switch" or "Nintendo has nothing to show, they already released their big games".
The concept may be the same, you are correct. But due to these expectations (that mean nothing in the grand scheme as shown by the Paper Mario drop), people panic when a direct does not show up at the usual time.
So the real difference is the perception of these announcements. Games can be announced within months of release more often, which will please a lot of people. Things can be shown when they are ready to be shown at anytime, rather than saving it for a direct or revealing it early. The information is the same, but the timing and perception changes.
Another benefit is that by shadow dropping individual announcements, there is potential for information to be delivered at a more steady pace as things will no longer be saved for a bulk announcement of sorts.
So it is not the information that will make a difference, but the perception of that information as a whole. A game could be announced at anytime it is ready, but a direct cannot. For example, if we get a FULL direct in June, we know not to expect another one till at least September. But if we get a game announcement or update in June, we could get another one for something different weeks or even days later. There is much more excitment in its own way.
Not to say Directs are bad and should be done away with, just stating that there is indeed a difference in perception that can be viewed as a positive when it comes to shadow drop announcements like Paper Mario.