In your example, you're contributing to other people projects so yes it would be contribution right of the bat. That's completely different than the case with ACF.
No, that's would be their value proposition or what every company on earth have been doing since inception, filling a gap in the market.
You seem to be claiming that their mere existence in the ecosystem would be a contribution, even if they were closed source. They would be providing value and attracting users in a butterfly effect style. Sure, that help and have a positive impact but is it a contribution to an open source project and the ecosystem?
My model is fairly simple, you can't claim credit for something if you did it involuntarily or with a different intention or it happened as n-level side effect of what you are trying to do.