Earlier quoted context omitted.
Seems only shitty if they are recruiting you to place your friend. Otherwise it could be read as, "hey these two developers seem to like each other and have worked together and we need more people". It could feel like a safer bet to hire people you know will get along.
Sure, but this discourages people who would otherwise be willing to provide references; if someone is willing to freely give you their time to talk to you about one of your candidates, it seems courteous not to potentially waste more of it by giving them an unsolicited offer.
> it seems courteous not to potentially waste more of it
...
or possibly not even be considering my friend