I don't think the Beta backers are asking for the game to be rushed in any way.. after all Beta testing is also a testing phase and it is expected to be buggy .. and will not effect to final product if all testing is done correctly.
Frustrations are bound to be experienced by (some) Beta backers, it's the nature of the beast ... the constant reply about releasing a buggy game has nothing to do with the release of the Beta ... As someone said .. If the Alpha still had not been released by now these forums would be going bat-doo doo ...
We all understand the need for patience, but I would really like my Beta now

(and some sausages ... nice Cumberland ones with some ketchup)
Simply put, you want it to be harder to sort out problems that should be singled out, by the procedure of adressing them in the proper order. This have a tendency to carry problems into later stages, which would include the Gamma.
Because when Beta arrives there will be pressure from those that want the Gamma! So the Beta must be rushed!
If we -again- have learned anything in the last 30 years, it is that retroactively fixing a mess caused by impatient people, problems carried into the next stage and never adressed when the focus shifted, is the best way to get bugs/issues that will never be fixed, because they will be embedded into further layers.
Rushing ANY stage comes with implications, for ALL stages. That is why we have stages in the first place! Stages like when you construct a building. You simply do not rush if you want a solid one. You simply do not move in before it is all done!
Rushing one stage for any other reason than moving ahead in proper order, however noble the intention, is to ignore the purpose of these stages, and make way for a lesser product for everyone, as happens every time the power of impatience is invoked. It always end up in a lesser product. Because that is the reward for rushing. Every single time.
Sadly this cannot be debated away, for we end up with a technical product, not a rhetorical essay. And we will all be affected by this. So please do not allow the power of impatience to get the better of this one...
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