Do they?
Last I checked 90% of the sports are either tournaments or you play everyone.
Unless by "all professional sports" you mean MMA and boxing
Yeah...? That is by design for entertainment purposes, not for "sports purposes". There is still matchmaking in them. Not all the divisions or conferences are balanced in terms of ability when there are times when they obviously should be.
Tournaments are also obviously designed to try to get big name teams to face each other in the end.
Boxing does have tournaments. World championships, the Olympics, Golden Gloves countless others. MMA has tournaments also...while we're here. The UFC does not have tournaments outside of the Ultimate Fighter - and the Ultimate Fighter
is definitely entertainment based, to say the least.
Can use the original K1 as something that is CLEARLY entertainment based first even though it heavily revolved around tournaments.
The fact that you think that sports leagues are not thinking entertainment first when they design regular seasons and post season schemes shows how good they are at their jobs.
Anyway, the obvious reason why everyone in MMA cannot fight each other each is because
- there's not enough time since people need to recover and train
- it's redundant and pointless for the best people in a league to verse the worst people even if occasional upsets happen, this literally only happens for ticket sales and media
Having a booker doesn't make something exclusively "entertainment first" more than a company that does not have a booker. You're seriously gullible if you think the NBA is a "real sport" because the Nets have to play the Thunder twice a year (whatever that means, NBA and UFC are not sports, almost every sport's top org is a bastardization of the sport and is for profit).
Professional and amateur sports have different goals, so obviously this is reflective in the matchmaking, regardless if it is from a booker or a regular season. (PFL has a regular season, it is less entertainment based than the UFC).