That is what I call pratice or bench racing.
Racing is a dynamic thing. You get one chance to put it alltogether with no do overs.
I agree that sailing has a lot of variables But there are a couple that you are leaving out.
Lots of other boats that you have to dodge on the start.
Boats the blanket your air.
Boats that pinch you at the mark.
Boats that cause you to change your tack because you are the burdended boat.
Things that break or become tangled or ripped.
Sailing in dirty air.
Personally I think PHRF racing is just racing aginst yourself.
If you are going to handicap the race then let the slower boats start with their handicap first so that the finish will be exciting, first boat over the finish line wins.
Just imagine a finish that might have 99% of the racers at the finish line at the same time and no big bunch up at the start.
Even if you start in the middle you will still be at the finish line with all the other boats trying to get that last bit of speed to cross the line first.
The slower boats would get a chance to see the faster boats sail as they near the finish line instead of watching them sail away only to be seen again at the dock.
As a racers what is more fun that passing other racers?
The world cruisers in their fat assed boat blowing on their sails as that 100 ft. tri Americas Cup boat is comming up fast, now that would be a sight to see.
Boat is competing against others by PHRF, sailing skill is a variable including selecting optimal wind and tide/current, course is fixed by three marks.
Repeat as many times as you want, until you have wrung the best possible time from the course, your boat and your skills.
The competition is sailing skills, and the potential benifit is to learn from others.