Well I can see one thing that kinda belies your point of view at present. Stability. Some people have presciently worried that their instance can implode, taking all content a user has made with it. Larger instances that are more stable, that have more backup infrastructure and ongoing commitment to operations, could out-compete smaller instances. Why this might arise, could be a historical accident of successful crowdfunding campaigns or something. I'm not sure how someone might do a better job of securing more server resources than others. Obviously a deep pocketed corporation who wants to influence the Fediverse, could do that.