Also, BJJ grew out of early Judo, which was less calcified when it was brought to Brazil. Helio Gracie was manhandled by the Judoka Masahiko Kimura, despite home-field advantage[1].

Catch wrestling also had similar rules, but had a culture of secrecy, so was not going to spread in a similar way to Judo.

Yet another reason is simply the fact that weapons were invented many thousands of years ago, so unarmed combat has been unimportant since at least the bronze age.

1: Of note, the Gracies thickened the padding of the mat used because Kimura's throws were known to be capable of concussing people; after throwing Gracie around like a ragdoll for the entire first round, he switched to trying for lock submissions, which he eventually did get (and BJJ names the shoulder lock used the "Kimura" even today).

I'm more interested in of the stand up combat sports like kickboxing.

I reckon UFC is missing out by not having a pure standup division, without the wrestling/bjj.

I know a former world champion kickboxer who says "Ground and pound? Where's the honor in that?". I thought about it a bit and realised he is right - where is the honor, sportsmanship in beating the heck out of someone on the ground.

The reason to include wrestling is that it makes the contest more closely approximate a real fight. In a real fight your opponent does have the option to go to the ground.

And be immediately killed by anyone nearby, who need merely step on their windpipe or something. Going to the ground gets you killed in a “real fight.”

But neither is likely at all.

Also unlikely: picking a fight with someone who weighs about the same amount you do.

Either way, I regret pursuing this topic and won't comment on it further since I feel this is a discussion not worth having, reading, or writing. I don't write that to be rude, just as an attempt to hold myself to some standard for discourse.