It doesn't need to be designed around solo players to the detriment of those who want to go in as a preset team. But equally they KNOW large percentages of folks do want that. The sensible solution is to make it win/win and whether you look at 95% of Seals, key weapon quests like Outbreak, Divinity, Whisper, Trials and it's loot, Raids and their loot, Dungeons and their loot, Clan rewards for doing nothing, Pinnacle rewards via Heroic to Master all out of the reaches of solo-play it's a WIN/LOSE scenario in these key areas. Those things compromise a lot more than 10% of the game - they are a sizeable chunk of Destiny2's development.