That musta hurt, telling people something constructive (pun intended) out of left field other than "I made this".
A chair will never be wide enough for some people... Charles Brock may never have heard of your favourite restaurant(S)... hell, a flat stool/bench is never wide enough for my fat rrrs.
That 1/2" short cant be blamed on the cold weather/water, and is a perfect example of how you can recover from some of the greatest oopsies. Maybe, could have been a greatest disaster, but you'll never know now, a maple insert, to match the dowels, could have morphed it from something you hated into a Pottzy treasured creation.
As for that tenon, blame it on Yankee policy makers... would never happen with a metric system... all your imperial fractions nearly always make things a fraction too short or too long.
If your first cut is too short... Take the second cut from the longer end... LBD