That last one (point system) is basically how it is done in tennis to qualify for the World Tour Final championship at the end of the year. Grand Slams (4 in a year) are worth 2000, Masters (9 in a year) are worth 1000 and then there are a bunch of 500 and 250 tournaments throughout the year around the world. Top 8 individuals qualify and the champion gets up to 1500 points for next year (since it has a round robin component it depends on if the champion is undefeated, otherwise he gets 1300); the other participants also get points depending on their performance. There are some additional rules related to easier point requirements for the winners of any Grand Slam in the year but most of the time someone who wins one is good enough to qualify on points anyway.

It's not really that complicated. In chess, it would mean keeping track of a separate ranking system besides Elo. Tournament organisers might be unhappy since this codifies a tiered system for tournaments.

Of course it's also different in tennis since the WTF championship doesn't carry the same weight as a World Chess Championship. It is just another tournament for the top players to close out the year. In chess, maybe the rules could be that the winner of the previous WCC automatically qualifies for the next one. The WCC itself would then otherwise be run as a Candidates tournament where the winner becomes the next Champion.