While the conclusion matches yours, I don't think the article you link supports your argument. I agree with the article in that I dislike the manipulative aspect of donation matching even if it's mild and for a good cause. However, it's not necessarily the case that a wealthy donor is donation matching instead of donating the flat amount to avoid donating more. It could be that a donor who is donation matching up to some amount X only ever intended to donate X, but wants to encourage others to help contribute a total amount of X+Y. If Y is below expectations, the donor can still donate the full X.

Whether this plays out like this in practice is different, and you would likely never hear about it because it would devalue the influence of donation matching if people know the donor will donate the full amount anyway.