Thanks to Nick Tune (@ntcoding) I submitted an EventStorming hands-on to the SpaConference in 2018
And what I discovered there is a completely transparent process . Right from the start, you can see each and every one of the submissions. And anyone can comment on the submissions. This might sound scary, but all of the comments I have seen resolve around better submissions.
Then a few week before the final decision is made, the submission are frozen, and anyone can again make a review.
This time it's more in depth review, not just comments, like classifying the submission, wether it it's the SpaConference preffered format (workshop & hands-on) Those review are not public at that moment, you just know that a certain number of people reviewed.
Once the review process is done , you get to see that actual reviews on you own submission; wheteher it has been accepted or not! This is an invaluable transparent process way better than "Sorry, You're not accepted, but try again next year"
I understand that for larger conference it's impossible to give personalized feedback. But my guess is that the openess of this submission process must be scalable in some way.