I get your point Best. However the world is a far from perfect place. So, rather than try to rail against the tide, it often helps simply to keep people abreast of what happens, and of course why, in order to present them with the ability to make 'informed choices'.
Without being rude, trying to file a flat on an end designed to take an olive is actually MORE likely to lead to a leak than simply fitting against the machined end.
Why?
Firstly, the filed end lacks the hard chrome plating of the original part which makes it more susceptible to both dezincification and flaking of the chrome plate at the boundary because of turbulence.
Secondly, the nitrile rubber used will often tear badly, or at very least set up micro tears, when set against a filed surface. Both of these
will cause it to fail far more quickly.
Whilst the best option is always to fit a 1/2" male iron fitting so you can tighten properly and guarantee a seal, using the limited smooth surface of a fitting designed for an olive will seal just fine so long as the seal is compressed no more than 20% of its thickness. Obviously the pressure that joint will be able to withstand is FAR less than the hoses rating, but for a 'normal' domestic situation (reasonably stable 3-5bar) it 'should' be fine. Any more compression or any more pressure or any large pressure fluctuations and it will fail.