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Debian is a notable exception.

I recommend reading "TCP/IP Illustrated: Volume 1, Second Edition" if you want to learn more about networking. Make sure it's the second edition, because the first edition is very old. The second edition is also over a decade old now, but it's still almost completely correct, as the basics haven't changed much. And don't mistake the book to be overly simplified because of the title; it's a very technical book that references the actual RFCs wherever appropriate.

In my opinion no OS manages such a feat of making itself unknown, there are always some problems, and I think you agree with that in practice (it's more a matter of thresholds). So there is continuous improvement. The question is then whether or not the possible financial boost from the donations will improve the OS in such a way that the net benefit is positive with respect to the negative value of the donation notification (a utilitarian viewpoint, I guess). I would say it will be a net benefit, not least because the negative value of the notification is so small.