In any contest/competition you are always going to get naysayers after the event (especially if they've failed to make the cut), it's an unfortunate fact of life.
As to post-processing I personally see no problems. I've seen many photos (and nominated several recently) where the PP made the shot what it was. Before PP it was probably an OK shot, after PP it became a stunning shot.
Let's not forget that photography is all about imagery, it's the final image that is important regardless of how many steps it took to get there.
I started out using film and manual cameras and even though I am now all digital I still try and compose in-camera and try to get the very best base I can before moving on to digital PP. In fact I'm only just getting comfortable with shooting multiple shots of a subject using different settings as my mind-set is still stuck in the 'each shot costs money so get it right the first time' mode despite using digital cameras for over 10 years!
Twenty-plus years ago I taught professional sound recording courses at a college in the UK and I always stressed to students the importance of getting the best sound you can through the entire signal chain from the microphone to the recording media (multi-track tape in those days). The old adage of 'garbage in, garbage out' applies to photography just as much as it does to sound recording.
Just my 2c.