THE phrase "The Old Firm" was not intended as a compliment.

It first appeared in a cartoon showing a down-at-heel guy on the street bearing a sandwich board which said "Patronise The Old Firm". Underneath was a cynical reference to "Rangers, Celtic Ltd". The message was clear: these supposed rivals were happy to privately work in cahoots to commercially exploit and dominate Scottish football. The cartoon appeared 108 years ago.

Back then the two clubs could meet up to 10 times a year in various competitions. Very convenient. Fans got wise to what was going on and rioted when the 1909 Scottish Cup final replay ended in another draw, necessitating a second replay and supporters having to turn up a third time for the same contest.

A century later one thing remains unchanged: these clubs make money for each other and they know it. They are bitter rivals who have gotten into bed together for four joint sponsorship deals in the modern era. They took the coin from CR Smith, NTL, Carling and currently Tennents because it made sense to support each other. They could get far more money together than alone.

"A lot of people think Celtic and Rangers need each other, well at the minute we don't", said Neil Lennon the other day. There are plenty in the Parkhead stands who seem to agree. The internet and Twitter is full of fans who can't contain their glee at the idea of Rangers' troubles leading to their obliteration.

They're counting down the days until the plug is pulled. There's humour in some of the jokes about the tax men and it's all fair game in a rivalry as intense as the Old Firm's. But if there are plenty of supporters who seem to mean it when they talk of "partying when Rangers die" there are just as many who realise exactly what it would mean for Celtic if they did. More trophies, yes, but swift downsizing, monotony and boredom. Every time Celtic sit down with a transfer target of any pedigree they hammer home the global interest and unique experience of playing in an Old Firm derby. The SPL is a helluva hard sell without that.

One former Celtic player told me the other day that he'd spoken to about half-a-dozen Parkhead old boys and every one of them wanted Rangers to survive. Punished, yes, but still around to fight another day. These are guys who recognise that some of the great peaks of their careers were goals and wins in Old Firm games. They understand that the glory is in beating bitter rivals, not wanting them wiped out. They can see way beyond the immediate Schadenfreude of seeing Rangers in the grubber.

To say Celtic don't need Rangers is to deny what feeds football. Supporters need to be nourished by tension, drama, and the edge which comes with ups and downs. They need real competition. Are some Celtic fans really, honestly saying they don't want any more Old Firm games? That they never want to watch their team beat Rangers again?

Where's the appeal in watching them plough through everyone else to win the championship by 25 or more points every season? Scottish football has enough of a credibility problem when only two clubs ever win the league; with only one it would be a laughing stock and a total non-event. There would be no return to the thrilling days of the 1980s, when Aberdeen and Dundee United won leagues. The financial landscape has changed within football and even a smaller, downsized Celtic would be far too strong for anyone else in the division.

The Sky Sports/ESPN television deal is essentially predicated on four Old Firm games per season. Without them, they would want to renegotiate at best and possibly pull out altogether.

Clubs already struggling to pay the bills would suddenly face significantly reduced income. Less revenue means lower wages and consequently poorer signings and less money to invest in youth development.

Fans aren't daft. More would turn their backs when they see that the football is poorer than ever.

Rangers shouldn't expect to find many mourners at Pittodrie, Tynecastle, Easter Road, Tannadice and the like. Supporters of those clubs would see their removal as dramatically improving their prospects of winning the Scottish Cup or League Cup. They would see it as another European place being freed up every season. It would end, too, the significance of the 11-1 voting structure within the SPL which effectively gives the Old Firm the power of veto on major changes. Losing the Old Firm game? As far as they're concerned, who cares?

But if football fans start to wish death on other clubs, even hated rivals who stand in their way of winning things, the game is up. If Rangers lose their tax appeal, their offence would amount to financial doping and they will deserve to be absolutely hammered. But big clubs are there to be loved and hated. That's part of the theatre. Rivalry is sustained by reacting to – and looking for a reaction from – the other lot. Celtic and Scottish football could live without Rangers but, boy, it would be as dull as dishwater.