And that is why I'll beat the drum again: Ars Magica already has books on adventures (Legends of Hermes, Tales of Mythic Europe), books on sagas and how to end them (Dies Irae, etc.), 'dungeoneering' books... but none of them do anything for new players and storytellers that want to play something of their own.
David mentioned in another thread that you cannot make a quick reference for experienced players and an introductory one for new ones alike, and while I agree with the general consensus that a 'Starter Set' would be quite welcome, that will not help the crowdfunding for ArM:DE, since they are different projects altogether.
What will help the crowdfunding is taking aproximately 20 to 50 pages of the book making sure anyone who has bought it can run an Ars Magica game without having to work out how to do it by themselves. If I'm either:
a) Someone who has a lot of experience running TTRPGs but I'm intimidated by the sheer amount of work ArM is to run, or
b) Someone who is relatively new to TTRPGs that gets enamoured by the system, the lore and the promise of the game as presented in the crowdfunding campaign, or
c) Someone who has run ArM in the past but doesn't want to jump in again without a clear way to jumpstart 'that saga I've been wanting to run'
Then putting that section into the book will only help drive up pledges and more people playing the game, creating a healthy cycle of new people coming, creating content, community, etcetera.
I will not claim to know more than people whose job is in the TTRPG industry, but to me this seems like something of a requirement if you want new people in on a very complex and overarching system as this is. 'How do I play this game? How do I narrate it?' are quite literally the first questions to answer.