"Fighting" Tai Chi was traditionally taught to people who were already very adept at Kung Fu. If you can already fight the form trains a bunch of clever footwork and a few other things at a really high level; it's _clever_. But if you can't already fight it has none of that basic stuff in it like "how to hit people really hard". If you don't know that already Tai Chi forms won't teach it to you every effectively.

Younger kung fu people wouldn't generally be so into Tai Chi. You'd learn it as you aged so that as you became less athletic you'd be substituting smart for strong and extending your lifetime as an effective fighter. All of this context was lost when it came to the west.

Also: https://en.wikipedia.org/wiki/Yang_Chengfu this is kinda what top tier tai chi people used to look like: neckless bears with fists the size of your head.

Also: weapons. In China open hand stuff is taught before you attempt the complexity of swinging round a sword but these were (and are) armed arts. Nobody shows up at a real fight without a machete or sabre I believe.