Why is fixed better on wet?

i hope im not repeating anyone but in terms of wet conditions caliper brakes on road bikes, regardless of pad choice and groupset, have vastly reduced purchase on the rim. ultegra and chorus brakes i have used will be 50percent less effective at stopping and as the aluminum-wet powder crap builds up and this worsens during wet rides. A fixed drivetrain allows the majority of decelaration to be done without skidding and even during wet conditions the tyre and road friction from a skid seems to remain effective in comparison to the concentrated and lubricated area of a brake pad on metal.

I've been told that cleaning the braking surface with acetate (nail varnish remover) massively reduces brake slipage in the wet... I have some lovely peach flavoured stuff... don't know if it works but it makes the bike and I smell nice for a few minutes!