I meant when you're not in a party. Destiny feels like a "shared-world shooter", even when you're running around by yourself. Not so, with The Division.
I will say the lack of matchmaking ruined Destiny for me and its thorough inclusion is part of the reason why I love The Division so much.
Yes, it's already very streamlined in The Division which is a good sign. You can be in a group of randoms for 90% of the time with ease even when you're just running around the map doing nothing. The main issue with the matchmaking is that it scales everything to the highest level player which obviously breaks down when you have big discrepancies between players.
Matchmaking is crucial in this game though since I don't believe it's anything special as a single player only game. I mean the story is serviceable and you can complete everything, it just starts getting really tedious after a certain level and you're trying to take down bullet sponge enemies by yourself.