The classes magic and ranged were introduced. Updates were released from the spring 2004 to OSRS gold the spring 2005. Magic and ranged received armors of the highest tier as well as various new attacks (i.e. the Ancient Magicks Spell Book) that give you greater access to arrows and runes. These classes gained more strength and were capable of competing with the melee class.
The calculation was the same. This allowed for a maxed ranged or magic player (let's say with 99 defense and 99 ranged/maged) to be level 100-110 as well as a maxed melee player to be at or around 120 levels. These numbers do not include hitpoints or prayer, so they are only estimates. This would give Ranged and Magic players an advantage over Melee in PvP situations.
We are currently in the Evolution of Combat update. The update balances the combat triangle. The three classes of combat are no longer "arguably equal;" they are undeniably balanced. Jagex developers decided to drop the formula for combat 138 (which saw the maximum combat level increase from 126 to 138 with Summoning), and instead install the current/past (depending how far in the future you look). The 200 formula considers all classes as equal. For instance, a player with 99 Ranged and 99 Defence will have the same level of cheap RS gold combat as a player who has 99 Magic and 99 Defence. Problem fixed, right?