Not true. Other sports that are coed or have high level mixed divisions:

Snooker

Croquet

Rifle shooting

Dog sled racing

Motorsport (Although tradition is still keeping many women out).

Sailing, albeit only in one class.

Women also fairly routinely compete against men and win in darts.

It's a very small number of sports, but it's factually inaccurate to claim it is *only* equestrian sports.

Also, there was a 40 something female archer in the Olympics a few years ago.