The point was made that a Marshall has invested real money to start a league. True. but you also have to take into account the players who have invested in leveling a fortress or beacons up, and now are sitting in a league where the Marshall has gone "long ago" for many weeks - halting all progress and upgrades, challenges, and diplomacy changes, especially if the Marshall has held all control. Not being able to manage these necessary league functions will kill a league.
Yes, you can start a new league and move players over, at the cost of abandoning all the league assets that everyone has worked for. From experience I can say that a league rarely recovers from this.
One solution to this would be allowing a Marshall to set a Vice-Marshall, or Co-Marshall, so if something happened to the founding Marshall the league would continue without major disruption and another player could be moved to fill the vacancy.
Until that happens, the only fair option is to allow an inactive Marshall to be replaced. It isn't an easy process, and it shouldn't be, but the option needs to be available.
We already have this option. If a current Marshall is MIA of 3+ weeks, a League can vote for a new Marshall and send ss to Support. But if their old Marshall comes back and claims his Rank back, Support will give it to him.
Until that happens, the only fair option is to allow an inactive Marshall to be replaced. It isn't an easy process, and it shouldn't be, but the option needs to be available.