- Isn't pre-installed on well known machines by well known brands.
- Popular applications (whether productivity, creativity, or games) do not work out of the box that people want. It doesn't matter that alternatives exist, or that you can use things like Wine. If it's more than just click the icon, it's too much.
- If things cannot be done purely through touch / the mouse, it is too hard for most people.
The Fediverse as a whole cannot be monetised, censored, or taken over by hostile entities.
Individual instances can, but they are only part of the whole and not the whole thing, so instances of Elon Musk or Steve Huffman simply cannot happen on the same scale.
As a fun fact of the day, Wikipedia subsists entirely on charity, so it's very possible to run things using this model if you provide enough value and transparency for people.