I was accused this week of being a wine snob. Plus ça change – I'm the editor of Decanter magazine – so no, when trying to source decent wine, I generally don't linger around the supermarkets' under-£5 bargain bin. But does that make me elitist?

The charge came from Asda, which took umbrage at my comment in an interview on BBC Radio 5 that "it's pretty impossible to get a decent wine at £3.99 or £4.99". The case against me was strengthened by the fact that a £4.20 Asda rioja had won a gold medal at our very own Decanter World Wine awards.

And very nice it is, too. But the fact remains that such bargains are the exception, rather than the rule (Asda's three other gold medals in the competition all cost £6 or more; of its 10 silver medals, only two cost less than £5; while of its 31 bronzes, just three would give you change from a fiver). The reasons for this are straightforward. At £4.55 (the average amount spent on a bottle of wine in the UK), more than half (£2.57) immediately goes into the pocket of the taxman. That leaves less than £2 to cover the packaging, bottle, marketing, transport, retailer's margin … oh, and the grapes. In all likelihood the wine itself represents about 50p – at best.

If, though, as I pointed out in my rejoinder on BBC Radio 4's Today programme on Friday morning, you shell out £6.55, that extra £2 is going almost entirely towards what's in the bottle.

In the days of a £3 pint of beer or cup of coffee, I don't think it's snobbish to suggest people spend £6.55 on a decent wine. So why does Asda believe it is? I fear it's part of a British disease. Would my aspirations be decried in France or Italy? I suggest not. So why are we Brits too ashamed to become wine buffs?

Much of it stems from prejudice. Raymond Blanc can tell people to spend more than £3 on a chicken because preparing good food is now part of our culture (and because he's French, I suspect). A Real Ale campaigner, though, urging beer drinkers to shun cheap lager, wouldn't be labelled a snob. So why are wine-lovers stereotyped?

It's a situation that several supermarkets have helped to create. By directing consumers to the "3 for £10" promotions, stores are hardly encouraging us to discover new wines. The wine industry's own trade body, the Wine & Spirit Trade Association, has even criticised such "deals", arguing that they stymie consumer education. Thankfully, after persistent tax rises that have now, belatedly, been passed on to the consumer, Tesco has said that the model is no longer viable (though Asda still persists).

There is a poignant paradox here. While British consumers are being led away from the wealth of choice that the wine world has to offer, UK supermarkets house the best, most varied ranges in Europe. It's just that some of them don't always want you to know it.

The other paradox is that Asda, laudably, has a master of wine in charge of its wine range. There are less than 300 of these wine masterminds in the world. Their knowledge is phenomenal. You would think, then, that the people at Asda would have wanted to harness this expertise to bring good-quality wine to the masses, and raise our wine aspirations – along with the amount that we're prepared to spend. So why do they hide their light under a bushel?!

If the price of wine were to rise, producers would be paid a decent wage to reinvest in their vineyards, we'd have better wine on the high street, and people would learn to appreciate wine rather than seeing it merely as cheap alcohol. I'm not going to get bogged down in the social responsibility arguments here, though they are pertinent. Instead – in the interests of even-handedness – where's that £4.20 rioja?