The team wants to stay together luckily, they opted to spend a full year playing in a tier 2 league in Korea (which is honestly just as good as OWL) to wait for Haksal to turn 18 so they could all join the same team.
Since Overwatch as a game is meant to have players be as flexible in terms of roles as possible, the player who plays Brigitte is actually the projectile DPS player, not a flex-healer, just like the Zarya player is the flex-DPS player. The reason this is like this is because Goats looks like this:
Main Tank: Winston/Reinhardt
Off-Tank: Diva
Flex-Tank: Zarya
Main Support: Lucio
Off-Support: Brigitte
Flex-Support: Zenyatta/Ana
Now compare that with Dive, another very strong team comp.
Main Tank: Winston
Off-Tank: Diva
Flex-DPS: Genji
Main Support: Lucio
Off-Support: Sombra
Flex-Support: Zenyatta
The reason it works like that is because in an instant, Haksal and SeoMinSoo can switch to Sombra and Genji and they are immediately playing a completely different style of Overwatch where they manage to keep 4 of their ultimates charged up. Also, Winston/Reinhardt is called Main Tank because they are the ones who stand in the front and soak up a ton of damage while making space for the rest of the team. Diva and Brig are off tanks/supports because they don't really do traditional tank/support things, but that's their role. The Flex slot is because they are the flexible position who changes to DPS or changes hero depending on what's necessary. Lucio is a main support because you can't play Overwatch without Lucio, he's not only the most important support but throughout the game's history he's been one of the most vital heroes regardless of team composition. Before Korean Contenders season 2, Haksal was known as a premiere Genji player. Stitch is the lead hitscan player and Seominsoo can play a bit of hitscan, a bit of projectile DPS and Hooreg is there to fill in if the team needs 2x hitscan or 2x sniper in the lineup at once.
If the Titans do decide to shore up their DPS however, there are lots of great DPS players around, DPS is the least valuable position to purchase because of GOATS and because it's the easiest of the 3 roles to fill, they can also purchase DPS players from other teams for just money, no player assets required.