There's no power vacuum. There's now a Mastodon nonprofit organization with an executive director and leadership team.
Keep in mind that every for-profit publicly-owned corporation has many shareholders, as well as a board of directors, which is, gasp, a committee!
At some point, you do have people that need to step back. If you turn it over to another single person, they could pivot and "ruin" the product. By turning it over to a committee, hopefully, any ruinous ideas get overruled. At least in theory