Sadly, that’s one of those technical things that may create resentment among “common players” but have very good reasons – and both points of view are perfectly understandable.
I wrote “common players” by lack of a proper word, maybe “the public” would be better, but whatever: please don’t read it as a “commoner”/“elites” distinction 
You clearly explained the common point of view – which is totally understandable as I said. But just taking one example: according the Kickstarter and Indiegogo, there are currently around 5,000 backers. If all of them have the possibility to post feedback and report bug as soon as the alpha phase is available, it instantly happens what is expected with such high numbers. Just imagine they have 3 bugs to report the first day, instantly the devs are facing 15,000 reports, and innumberable discussions.
There is also to count on the fact that most of those reports would be posted in 50 or 100 duplicates, but still would need to be sorted out, policed, there would also need to ask for the screenshots and saves constantly missing, etc. The clear conclusion is there’s an urgent need to recruit some QA people to do the job, which is not that much efficient as it essentially means sorting out reports.
The policy by the devs for A.C. is far more efficient and reasonable: if you have an alpha with 50 testers (around 30 archeologists and historians, 10 shaman & deity backers, maybe 10 others people the devs trust), then they know the people testing the game, each one may be progressively specializing (UI, content, AI, sounds…) then have naturally a close connection with the devs in charge of their peculiar field of testing, which create very soon some trustful relations.
This allow for an increasing number of bugs to be efficiently fixed, with higher and lower priorities being easily defined.
A second step is the closed beta, were you may have more testers, then the open beta, when you may see a number of issues noted earlier: duplicates, lack of explanation, no saves so no repeatable situations & bugs, etc.
Naturally, at the moment of the release, there will be an horrible number of bugs, that will be reported instantly with a fair number of wooing (“How could your testers have missed such a thing, you clearly should fire the instantly!”). However, there is then to take into account that e.g. 15,000 players playing 4 hours the first day will have seen as much different situations as 4 devs playing 15,000 hours, or 1,000 testers playing 60 hours, etc. So nothing unexpected.
But all in all, the 4 devs (maybe 5 or 6, but never enough in one case or another) will have managed to treat an immense amount of bugs, in the most efficient way given they are human brains and (still not) mechanical coders.
). This is the moment you can give the game to a wider public for testing purpose.
