Had they said "the array will be so large it'll have its own gravity." then you'd be making a valid point.
But they didn't say just "gravity", they said "gravity well".
> "First, let us simply define what a gravity well is. A gravity well is a term used metaphorically to describe the gravitational pull that a large body exerts in space."
So they weren't suggesting that it will be big enough to get past some boundary below which things don't have gravity, just that smaller things don't have enough gravity to matter.
Given all mass has gravity, and gravity can be metaphorically described by a well, all mass has a gravity well. It is not necessary for mass to capture other mass in its gravity. A well is a pleasant and relative metaphor humans can visualize - not a threshold reached after certain mass.
"Large" is almost meaningless in this context. Douglas Adams put it best
> Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space.
From an education site:
> Everything with mass is able to bend space and the more massive an object is, the more it bends
They start with an explanation of a marble compared to a bowling ball. Both have a gravity well, but one exerts far more influence
Had they said "the array will be so large it'll have its own gravity." then you'd be making a valid point.
But they didn't say just "gravity", they said "gravity well".
> "First, let us simply define what a gravity well is. A gravity well is a term used metaphorically to describe the gravitational pull that a large body exerts in space."
- https://medium.com/intuition/what-are-gravity-wells-3c1fb6d6...
So they weren't suggesting that it will be big enough to get past some boundary below which things don't have gravity, just that smaller things don't have enough gravity to matter.
Given all mass has gravity, and gravity can be metaphorically described by a well, all mass has a gravity well. It is not necessary for mass to capture other mass in its gravity. A well is a pleasant and relative metaphor humans can visualize - not a threshold reached after certain mass.
"Large" is almost meaningless in this context. Douglas Adams put it best
> Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space.
From an education site:
> Everything with mass is able to bend space and the more massive an object is, the more it bends
They start with an explanation of a marble compared to a bowling ball. Both have a gravity well, but one exerts far more influence
https://www.howitworksdaily.com/the-solar-system-what-is-a-g...