Competent drivers ? Mistakes are made all the time, some unwitting, unintentional, some more deliberate but even within this discussion by cyclists, theres been confusion as when to use lights and what to use...so perhaps automating it with DRL s can have some benefit.
Your second point, obscures the presence of other road users, I honestly have seen no evidence of it (while accepting that's just me so there MAY be some circumstances in which they may) ...but given I'm a careful driver, I have NO problem seeing everything and everyone and DRLs on other vehicles have presented me with NO known hinderance whatsoever.
I'd buy the arguement in general if the evidence supported it but I'm yet to be convinced.
Next time a modern Audi is coming towards you, watch it closely.
In the early 80's Honda did a lot of research into daytime lighting. At the time they owned the worlds largest searchlight manufacturer. so had a lot of expertise on optics to call upon.
They discovered that over-bright lighting during daytime conditions increased the chances of certain types of collision, mainly T bone incidents. The human brain calculates the speed of an oncoming object by the rate at which it increases in size in relation to the surroundings. Over bright lighting breaks up the outline of the vehicle, thus depriving the observer of this datum, making it harder to accurately calculate speed. Something as innocuous as normal dip-beam headlamps being illuminated on an otherwise good visibility day was enough to trigger this phenomenon.
Suzuki were later to do similar testing and research, albeit smaller in scale, and repeated Hondas findings.
The human brain has not adapted to benefit from lighting in good conditions because such lighting does not exist in nature, where lighting is provided by a point source at a separate position to both observer and observed.
So when you're next able to do so, take a moment to watch that Audi. With an awareness of the above phenomenon in your mind you can actually see how it deprives the observer of a proper view of the outline of the vehicle as it approaches. The effect is visible to anyone with eyes and an awareness of the effect. Because you're a careful driver like me who takes their time the impact upon you is minimal, but for the average road user who flies about the place and leaves little room for error something as small as that can be enough to trip them up.
As an aside, I'm sure you meant no Ill, but could I ask you not to emphasis words with caps like that please? I'm dyslexic, and that really makes text difficult for me to read, which is doubtless the opposite effect to that which you intended