The incentive might become more apparent as time goes on.
long term up-time commitments
stability guarantees
dedicated Moderation services
dedicated help service
performance guarantees
additional features or parallel services beyond ordinary masto (eg search, blogging, feed sorting/algorithms, or even fusion of additional platforms like lemmy)
active sponsorship of developers contributing back to masto
subscription is part of a dedicated app too (see, eg, Mammoth)