Why would it be damaging? Its up to a player themselves to summon someone. If you're not into summoning people and battling bosses yourself then who cares?
This is an online game with coop and pvp. Balance is the most important thing in any game and when it's online, even more so. The article does a pretty good job at explaining why being able to summoning someone 20x your level is extremely damaging to the community.
Also does anyone know how to make a link clickable?
The coop is again only for password-specific summons. If someone wants to summon someone around their level they still can. The PVP was busted to begin with at that. Invading somebody only to find yourself squaring against three players is already a steep hill to climb. It's even worse when they're potentially much higher level, but you're already at such a disadvantage anyway that it doesn't really matter that much.