Belief can be a wonderful thing, but it can play havoc with your judgement. Take social media, a phenomenon that is changing the face of global communication in a way that largely speaks for itself. But is it changing the world of business, or legal services? You'd certainly think so from the emerging band of self-styled online gurus and hardened internet utopians that spare no opportunity to tell law firms that they need to get with it.

A common defining characteristic of this breed is heavy deployment of ecological allusions in which law firms are told that they need to 'evolve or die'. While not always spelt out, said evolution seems to involve spending less time foraging for sustenance among bluechip companies and banks and rather more time using the new hunter-gatherer tools of blogging, tweeting or whatever verb you use to describe messing about on Facebook. To listen to some of this crowd you may conclude that having an awesome corporate Twitter account is the developmental equivalent for law firms of fire, the wheel or opposable thumbs.

Those that don't lean quite so shamelessly on the Darwin sometimes favour a bit of Marx, opting for revolutionary comparisons over the evolutionary. Get with the bold new world or get left behind. New paradigm, or whatever. Less poetic souls sometimes just assert that law firms 'need' or 'must' get into this stuff.

Much of this is either total nonsense or rests on airy assertions. Corporate law firms don't 'need' in any meaningful sense to blog, tweet or otherwise mess about with social media. Their success or failure is defined by a host of factors, among them quality of the partnership, current client base, client service, infrastructure and ability to hire, motivate and retain good staff. To be fair, use of technology would certainly be in that important list, but the subset of social media currently has next to nothing to do with the success or failure of a large law firm.

There are reasons for this. Most obviously, these are institutional advisers, very rarely focused on even the high net retail market. They've already got a good idea of who their clients are, and they've largely got them covered through client relationship programmes and old school schmoozing (the social without the media bit). As such, the use of standing out via social media, while not non-existent, is still far from compelling with the exception of hitting the undergraduate recruitment market or setting up alumni networks.

And, frankly, there are far more obvious holes in City law firms' communication and marketing skills than duff Twitter accounts and risible blogging – most notably the dysfunctional manner in which many law firms run what they call – apparently without irony – 'business development'.

Now if I'm sounding like a luddite or my old man, that's not to say that that there's nothing in social media for law firms. For smaller firms, or those in clearly defined niches, especially with a strong focus on retail clients, there's obvious mileage in sticking out in what is a hugely fragmented market via use of social media. Indeed, there's already half a dozen or so law firms in this camp that have attained a profile that would have been unthinkable a few years back using just these tactics.

And even for corporate law firms, it surely makes sense to make some efforts to utilise social media. That's not because the ROI on setting up your own blog yet looks anywhere near compelling, but more because law firms already spend large sums of money producing legal briefings, research and market material – it's just that they don't use social media to deliver it. Given that they are already committing considerable resources to producing said content, it would make sense to reallocate a bit to tap into forms of communications that are increasingly being used by staff and clients.

I still remain of the view that at least one top City firm has a decent corporate law blog in it waiting to get out and, given the dearth of effective blogging in the area, any major firm that pulled it off would certainly stand out from the crowd. You could also make a case that a really ambitious corporate law firm could use social media as one means of many to drum home their progressive credentials.

Another sound reason to make some targeted excursions into social media land is that it offers a modest hedge against the future. It's already pretty plain that social media represents a huge shift in how people will communicate in the future, even if working out how it will play out in detail is just guesswork. But if you haven't spent any time or effort at all building up skills on how blogging or social media works, you'll have to play catch-up if it really takes off for business use (and eventually, it probably will).

Consider that in practical terms. A sizeable firm asked me recently if I thought it was worth setting up their own Twitter account. I said you need someone reasonably on the ball and motivated to take responsibility for it, it will take a least an hour a day of their time and it will take six months to a year before you build any kind of momentum. If you're prepared to accept that, then it's a nice communication tool to have, but it's certainly not yet essential or any kind of magic bullet. But you rarely see social media discussed in such practical terms for a business audience – it's either revolution or fraud.

And that's the problem that the online devouts have when they preach the virtues of social media to senior lawyers – in believing so strongly, they over-sell the virtues. This kills off the interest of a sceptical audience that remains highly attuned to bullshit and always on the lookout for good reasons not to change. But then it's tough to sell a rallying cry for lawyers of: 'Social media – worth it soon. Probably'.