If we have to historiographically trace the establishment and development of the symbiotic relationship between sport and media we can pinpoint a specific time and place in Western history: Victorian and Edwardian Britain.
Socio-cultural changes in the British isles such as the rapid industrialisation and urbanisation were accompanied by developments in how we understand today mass media and (professional) sport. As Niklas Luhmann argues (see book here) mass media can be comprehended as the different institutions that used a particular technology (print copying and broadcasting) to disseminate content. We can add to his understanding of mass media the establishment of commercial media that happened concomitantly at that time – it was the realisation that profit would not come strictly from selling print copies to readers but of selling spaces on those print copies to advertisers. In a way, the battle for eyes/readers/audiences and ultimately attention began long time ago (see YouTube video below about attention merchants)
And how to draw the attention of more readers and viewers and thus charge premium prices for those spaces? By having the best content possible!
Here comes the symbiotic relationship between professional sport and commercial media that developed to a point during the last hundred years where it becomes almost unimaginable to think one without the other. The quest for the ideal media content that could draw almost endless attention was probably over before it has even started. Professional sport as another byproduct of Western modernity (commercial media being another example) provides media with the ideal content because of its intrinsic characteristics such as: reality factor; international literacy factor; regularly scheduled and cost-effective factor; loyalty and effects factor; benign factor; zap-proof factor; promotion factor; and integration factor (see Bellamy, 2013 for an explanation of those factors).
In a way, we can say that media needs sport as much as sport needs media. One without the other is not only unimaginable, as it might be unfeasible. And the Covid-19 pandemic provides a perfect example where the sedimented symbiotic relationship is put in turmoil. What will come out of it is yet to be seen, but we might be witnessing another disruption to this relationship.