If the 7th ed gives 'concrete examples' then I would suggest they are just that, not an exclusive description of any and all situations in which sliding can occur. I still think (just my opinion, however - I am not claiming certainty) that the quotes from 8th, given above, express a spirit in which clipping should be avoided, especially the quote on BRB p.20: " ... As many models as possible from the two units must be brought into base to base contact." // "... what would happen in a real battle is that the warriors of the two units would quickly move to attack their enemies ..." This I very much agree with. A clipped combat taking place seems wrong, moreso than most other 'tabletop' conventions. In reality some sort of folding around would occur in such a situation, or the attackers would end up mostly on one flank. The rules don't allow this for simplicity reasons, so we would allow sliding as the simplest of all resolutions - often sliding both units a little. The end result seems as close as to what might happen in an actual battle as we can get.
But ... like I said, although this is a 'house-rule' it is very much done in the spirit of the rules (that quote) and the spirit of Warhammer rules from the past (we've all been playing over many rules' sets, myself since 1st ed). Besides, our campaigns involve army lists from previous editions (by necessity), campaign army lists from internet campaigns, and campaign rules modified from a combination of Mighty Empires, General's Compendium and other campaign mechanisms. Sliding is probably the least of our 'sins'. Rules lawyers would hate our campaigns!