I'm not sure you are having the correct definition of meritocracy in mind. A meritocracy is a system where the actors who provide the most benefit to the society, benefit the most. However, in chess, tennis, etc., there is no real benefit.
Originally it was coined as a satirical characterisation of a hypothetical stratified future society so obsessed with test performances in early years that all power became concentrated in the hands of adults who had demonstrated youthful aptitude and were thus assumed to not need to prove themselves any further thereafter since competition could only demoralise lesser minds; the author took the view that the "merit" of passing test thresholds would often be dependent on access to sufficiently expensive early years education and would resemble and often simply be a justification for upholding traditional social class divisions
As for tennis, I think it's fair to say that tennis fans consider Federer et al to provide them with considerable enjoyment, and far more so than less talented players whose games they don't watch, or indeed most people working in non-entertainment jobs who can only help a few people at once and/or find it difficult to prove how much better they are than other people in the same role
The problem here is that "meritocracy" reduces to "free market", where everybody is simply paid for the benefit they bring to others, and where only the few best win.
And my original point was that meritocracy wasn't even originally conceived as a "good thing", never mind a utopian distribution of wealth and power allocation according to some ideal standard of social utility. Other people have subsequently chosen to [re]define meritocracy as some sort of aspirational standard for allowing more talented people to succeed; people defining 'meritocracy' with respect to the propensity of that skill to generate revenue are making as valid a use of the term as anyone else.
Where X is [machine learning, tennis, chess].