@Neil *******
that is correct. It's no longer published as such by IATA but I don't think the actual rule has changed.
But keep in mind that proof of onward travel is required for the visa application instead when getting a tourist visa. So proof of onward travel is required (at any stage) whenever you come as a tourist. An embassy can however decide to still give you a visa even without proof of onward travel, they have discretionary right on it.