Melee or Ranged attacks by Monsters, no distinction in modifiers?

Question

Weapons with the Thrown property can be utilised as both as Melee as well as Ranged weapons. When used as a Melee weapon, you base the attack+damage rolls on Strength, otherwise on Dexterity (unless it's a Finesse weapon, in which case you decide).

My question:

1. Why don't I see this reflected in Monster statblocks? I've been going through the MM, and never have I seen this reflected (ie. the attack and damage are not specified specifically for melee/ranged attacks). Is this to keep it simple, or shouldn't you make this distinction when it comes to Monsters? And thus:

2. Should I follow the attack roll and damage from the action as described, or calculate it differently depending on if the attack is a melee or ranged attack?

For example, looking at the Ogre (MM p. 237), it reads for the Javelin:

Javelin. Melee or Ranged Weapon Attack: +6 to hit, reach 5 ft. or range 30/120 ft., one target. Hit: 11 (2d6 + 4) piercing damage.

Since the Ogre has a +4 Str and a -1 Dex, the attack and damage rolls are clearly based on Strength. Now, what if this Ogre decides to hurl that Javelin at someone, should I use these numbers or figure out that the Ogre is a CR 2, thus has a proficiency bonus of +2, thus the Attack roll would become +1 (2-1) and the damage roll -1?

Answer 1

The reason you see no distinction is that there isn't any: thrown attacks default to the same modifier the weapon uses for melee attacks. From the "Weapon Properties" section of the Basic Rules on D&D Beyond:

Thrown. If a weapon has the thrown property, you can throw the weapon to make a ranged attack. If the weapon is a melee weapon, you use the same ability modifier for that attack roll and damage roll that you would use for a melee attack with the weapon.

There is no reason to recalculate monster modifiers.

Answer 2

The description of the Thrown property, PHB, p. 147 contains the following sentence, emphasis mine:

If the weapon is a melee weapon, you use the same ability modifier for that attack roll and damage roll that you would use for a melee attack with the weapon.

There simply is no difference between the (damage) modifier for melee and ranged attacks with the thrown weapon.

Javelins cannot be used with DEX in melee combat, therefore DEX cannot be used to calculate the attack modifier/damage for Javelins.

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There's nothing preventing a monster to use one of it's melee weapons as (potentially improvised) thrown weapon, but they do not carry multiple weapons, unless Ranged is mentioned, see MM p. 10f:

ACTIONS
When a monster takes its action, it can choose from the options in the Actions section of its stat block or use one of the actions available to all creatures [...] as described in the Player's Handbook.

[...]

AMMUNITION
A monster carries enough ammunition to make its ranged attacks. You can assume that a monster has 2d4 pieces of ammunition for a thrown weapon attack [...].