There is some mechanism on our brain which means that an image presented to both eyes will appear brighter than a "same brightness" image only presented at one eye. So i guess you could say that less good binos may be able to give as bright an image as a better scope.
On the other hand if you don't spot the deer then you will never start to stalk in to them. So with excellent binos you might spot deer that you couldn't see clearly in the scope and then stalk in until you were able to take a shot.
I think the other problem with scopes is that there seems to be an attitude that you "need" lots of the bells and whistles the marketing men try to punt to sell more scopes. You can buy best quality 2nd hand, fixed mag scopes ideally suited to stalking in the £200 - £400 range and you'll never need anything else.
Also marketing is a big thing in the bino market as well and the biggest magazine ads, no matter what their claims, do not always mean the best glass. You'll get a set of Minox HGs second hand for less than £400 and you'll not need better last light performance, nor will you get it unless you go for top end Zeiss and the difference will be marginal.
Given all this you can have top notch stalking performance in both binos and scopes for £400 - £800. Many of the magazine adverts would have you spending 4 or 6 times this amount. If you are sensible, ignore the marketing hype, and buy what you actually need rather than stuff you might fancy then for a fraction of the money you see in the adverts you can go stalking without compromising on either binos or scopes. A win-win solution.