We can certainly observe that the location for growing grapes is a very important factor in the quality of the juice for producing wine. This is why named locations such as Champagne, Bordeaux and Burgundy are so important to the quality of the wine, and that very little wine is grown in France outside the known good locations. We can also observe that practices in the vineyard also make a huge difference to the quality of the wine. So, whilst there may be more than one good way, there are certainly very many bad ways for growing grapes that have a detrimental effect on the quality of the grapes for making wines. We can also observe that a glass house, or a container, are completely useless ways of growing grapes for wine production - no one does it, even when free from European regulation. I think it suffices for you to know that this is the case, and is clearly demonstrated as such, rather than any particular reason to know "why", and in any case the answer to "why" in relation to many of these details is not well known, despite serious attempts to find out. We do know that the drainage structure of the soil is more important than the chemical make-up, though the latter is not totally irrelevant, and that the roots need to find their way deep, very deep. But in general finding out what to do to get acceptable wine has been to a matter of trial and error over the centuries.

However in the case of growing the grapes in a container and/or a glass-house, I think we can guess the likely reason for the unsuitability - grown in such an intensive fashion the grapes will contain too much sugar and water and not enough of the acids, polyphenols, and other trace flavour components required for good wine, and will be too far out of balance in that regard to make any kind of acceptable wine.

Wine grapes are usually perfectly edible if fully ripe - sweetness is an essential part of both edibility and suitability for wine making. Certainly I know from personal experience that grown somewhere like Central Chile (the equivalent climate of Portugal) Pinot Noir is sweet and fragrantly aromatic in flavour to eat. But even grown there the grapes are very small, tiny little things, with lots of pip, falling well short of ideal for eating out of hand. If you are growing them for eating, better to grow something that has that purpose. Better to grow something that you will get to that level of ripeness for eating.