Github isn't a public good or a person; it's a product for a for-profit company, whose aim is to squeeze profit out of you. They care nothing for you and will dump you the moment it's profitable.

I would invest your energy in something worthwhile like an open source project, a non-profit, a social or political cause, a family memeber, etc.

> Occam's razor applies here

I think the simpler explanation is clearly that it's a for-profit company and these problems aren't worth fixing, and not a speculative engineering excuse. If Microsoft wanted to invest more, including in uptime, they could make it happen. They have over a trillion dollars.