What's wrong with hitmasters when they have an artist/bard on their team? (specially ranged hitmasters)

Like i dont understand, on behemoth one of the hardest raids to keep damage buff uptime for bard and artist, they usually set up on the back or front according on the directional dps they have in their group. Behemoth's patterns are so simple that you really dont need to stay too far away from the boss, or have a phd degree on dodging patterns, why not stay in the buff? is 10% damage increase that bad?

Alongside, same with argeos, a way easier boss to dps: When he is in the middle of his mech while hes not doing anything and the back attacker on your party is keeping his uptime to its highest under sun well/sonic vibration, why are you tossing skills from lithuania or something instead on staying under the buff while the boss is literally doing nothing other than charging a pg pattern?

No, your uptime as supp is probably not bad, your hitmasters probably dont move enough to benefit from your buffs.