It's that the 'resource' (ie all the archaeological information under the ground) is finite at Avebury. So yes you can dig (as they did at one part of the purported Beckhampton avenue) but you can only dig a bit at a time. You learn something this time. But you leave a bit left so people can learn stuff in the future. So yes, you can dig, you can 'restore' (provided you know what was originally there to restore it, I suppose) - but you don't take a unique and nationally (internationally?) important site like Avebury and dig it all up, restore it all up, at once.
1. it is because of all you've expressed that I tried to say something early on in this discussion to the effect that anything that's done at Avebury has to be a compromise between what we naturally would like to see done in our time and what is left for the future to do better in it's time. A compromise being the only way such irreconcilable interests, those of us and those of posterity, can be eve be resolved.
2. it is why, for the same reason, EH's guff talks of sampling around 2.5% when investigating a site - or it might have been 5%, it's donkeys years since I read it. Anyway, the thinking is well established worldwide, eat only a bit of the pie else there'll be no unchewed pie left for the great grandchildren. And it's important to keep in mind "we" are the minority compared with the future so we ought to take a very modest slice in all fairness.