Other folks are also noting that, because humans are sometimes bad at evaluating each others' intent, it is probably a good idea to attempt to make one's intent clear if going this route, lest you annoy the gatekeeper.
https://www.coindesk.com/coinbase-bitcoin-app-apple-app-stor...
https://venturebeat.com/2014/12/14/bitcoin-wallet-coinbase-n...
This is what is wrong with walled gardens, laws should be made by lawmakers, not Apple.
I'll take it down a couple of notches to make it easier: HN could serve every user under the Sun and still be entitled to have a (perfectly legal) rule that says "Don't solicit upvotes". No amount of "oh but at their scale" will change that.
Apple, Google, Facebook, etc. or any company actually do not write laws (they lobby and bribe for them but that's a different can of worms). They just write their own rules for their own products and services. Those rules have to be within the law and even if common sense and current evidence may say they break the law, it's up to a judge in an antitrust lawsuit to decide.
As I tried to explain above, HN is free to have a rule which says "Don't solicit upvotes" but they can't have a rule "Don't talk to women". The simple answer is because no matter what that rule says, tit's not a law, it's just a rule which can be applied only until a judge decides it's against the law.