This would work nicely IF there were dozens of masters of all skills applicable in the fight.
From the last invasion in Yrkanis, this isn't always the case. There the only way to eventually kill the boss was to pull him on the karavan guards who're invincible yet do massive damage.
Eventually (after some 10-15 minutes) the guards managed to kill the boss while all players were long dead several times over (as were all the city guards).
Making bosses harder or even impossible (if they 1-hit anyone they strike they're effectively impossible to kill) to kill most people simply wouldn't bother (after the Matis exterminator, the number of people going to Fairhaven to take on the one there was even lower, in your scenario hardly anyone'd have gone at all).
Boss mechanics, requiring more coordination among the large number (50+) of people now needed to eventually kill them would be even worse. It's simply not feasible with our population and game systems.
From the last invasion in Yrkanis, this isn't always the case. There the only way to eventually kill the boss was to pull him on the karavan guards who're invincible yet do massive damage.
Eventually (after some 10-15 minutes) the guards managed to kill the boss while all players were long dead several times over (as were all the city guards).
Making bosses harder or even impossible (if they 1-hit anyone they strike they're effectively impossible to kill) to kill most people simply wouldn't bother (after the Matis exterminator, the number of people going to Fairhaven to take on the one there was even lower, in your scenario hardly anyone'd have gone at all).
Boss mechanics, requiring more coordination among the large number (50+) of people now needed to eventually kill them would be even worse. It's simply not feasible with our population and game systems.