I got this idea while trying to find a solution to the problem of MMORPGs having a limited lifespan.
After reaching the maximum level and obtaining the best gear possible in the game, most players get bored and leave, unless the devs release a new expansion raising the level cap and adding new gear.
Before I begin, I should tell you I don't like this idea at all but I wanted a second opinion.
In this levelless MMORPG of mine there is no progression, weapons of the same kind have the same stats but different types of weapons have different stats. For example a viking sword would have the same attack power and attack speed as a roman gladius but not the same atk power and atk speed as a battle axe or a dagger. Damage is dealt based on a percentage of the target's maximum health so instead of hitting a mob for 120 damage, you would hit it for 4% of its maximum health, same principle applies in pvp. That means as soon as a you enter the world, you can kill any mob from any zone in the game or defeat any player regardless of how many hours they have sank into the game. Players are given a limited number of skill point to spend and can reset their skills only once per character.
That is the core of the game. I know I left out a lot of things like classes, races, jobs etc but I didn't want to focus on them in this post.