And isn't that convenient? Google's main kind of link-selling is unaffected by their rules, but other kinds of link-selling is disadvantaged. ("Use a standard we invented to make our job easier, or risk being frozen out of 70%+ of all search traffic.")
And similarly: "We crawl your stuff; but our search results are off-limits." Of course, anyone can block Google, but given the asymmetry in business models and market power that's not much of an equalizing factor.
I like Google and think they mean well. Individually each of these policies has a reasonable basis. But Google is now so dominant -- and the positive financial rewards they get from self-serving policies so large -- that their actions deserve close scrutiny.
(The Freud-inspired quote I led with was originally about the state; Google's influence on the net is so large that they are a lot like the net's government.)