Mikhael is a level 4 human ranger, variant human, Sharpshooter and Crossbow Expert feat. Dexterity score of 16. Archery Fighting Style. Hunter Archetype. Horde Breaker chosen at level 3.
He encounters a pack of 8 orcs, 60 feet away from himself. This is a challenge rating 4 encounter meant for a party of 3-4 adventurers. He triggers the orcs, and initiative is rolled.
Mikhael wins initiative, goes first. -5 penalty on the attack roll +10 to the attack’s damage. Hits. (After all modifiers accounted for, he has a +2 bonus to attack the AC 13 orc) He has a +10 to the damage roll, adds his +3 dexterity modifier, rolls the hand crossbow’s damage of 1d6.
Total damage is 15 piercing. This is the orc’s health, so he dies.
Uses bonus action to attack again with a hand crossbow he is holding.
Orc is 5 feet from the another orc. -5/+10 again, and he hits. Rolls 1d6+13 and gets a 4, dealing 17 damage and slaying the orc.
Because he made a weapon attack, he can make another attack with the same weapon against a different creature that is within 5 feet of the original target and within range of his weapon. -5/+10 but dice are good, he hits. Rolls his 1d6+13, gets a 3 on the damage roll, slays the orc.
The remaining orcs then spend their turn becoming no longer surprised.
The ranger moves 15 feet, bringing an orc on the outskirts of the group that was previously too far away into his long range ... rolls without disadvantage ... -5 / +10. 15 damage which kills the orc. Then, because he used the Attack action and attacked with a one-handed weapon ... hits. using bonus action to attack with a hand crossbow. Hits again, 15 damage and slaying the orc. The orc was standing within 5 feet of another one, so because he made a weapon attack, he can make another attack with the same weapon against a different creature that is within 5 feet of the original target and within range of his weapon. hits, dealing 18 damage and slaying the orc.
The two orcs, aggressive as ever, use a bonus action to reach 15 feet away from the ranger and then finally move 15 feet to enter melee range. Both bring their greataxes to bear, dealing 18 damage to him. The ranger, who has a minimum of 25 hit points at this level, still retains (at minimum) 7 hit points, survives. It is now his turn.
He turns his crossbow on one of the two orcs and, because being within 5 feet of a hostile creature doesn’t impose disadvantage on his ranged attack rolls, he attacks the first orc. hits. -5/+10. 16 damage, slaying the orc. He then turns to the next orc, using bonus action to make an attack -5/ +10. 15 damage because of it. He slays the last orc.
Everything here is accurate according to the rules.
This is an extreme example, but the crunch is this: the Crossbow Expert feat and Sharpshooter feat are easily exploitable in this manner with little else, and the penalties for extra damage are... Kind of minimal. So... How do you, as a DM, deal with this cheese and cheese like this without outright going "no, you can't do that"?
Do you sculpt combat around them to the detriment of other characters? Do you talk with them about it, and, assuming they're willing to talk it out, how do you remove this sort of business? Should you just accept it?