“If LA is so desirable why isn’t there a team there already...”
Because the politicians in LA won’t bend over for the NFL the way they do in most cities.
“...and why can’t LA keep a team there?”
Because other cities WILL bend over for the NFL.
There were pro football teams in LA for longer than the Jags have been in existence. You might keep that in mind.
“There were pro football teams in LA”
Exactly,”were” as in not now.