The nominal subject of the article is "friends", but it appears that the article is best understood as about work friends. Perhaps "allies" would be a more appropriate term? I hope that the author has some work/life balance and can feel the difference between these two categories.
I would define a friend as someone with whom you enjoy spending time. There doesn't need to be a goal except to "hang out". Do you really need a friend to "give meaningful feedback on your projects"? The author's conception of a friend, in the article, feels starkly utilitarian, where friendship is a tool for achieving your other ends rather than an end in itself.
If we interpret friends here as work friends, then I think a little jealousy and zero-sumness is natural. The very first benefit mentioned by the author of rooting for your friends is that it "can improve your career". If your work friend's career improves, but yours doesn't, then doesn't that defeat the (author's) purpose?
> It’s deeply believing that a rising tide lifts all boats.
I deeply believe that this is utterly naive.
It's not inherently false—we could make it true, if we really wanted—but it's empirically false, for the obvious reason that those who are lifted tend to be greedy and want to keep all the gains for themselves. Whether that's because power corrupts, because power attracts the corrupt, or some combination of the two, the problem is that those at the top come to feel that they deserve to be at top, that they're better than those who are not at the top and have been rewarded for their superiority, and thus from their perspective it would almost be immoral to "reward" those below who aren't as "good".