Oh, it's definitely not because LAFC has a ridiculously good team, or anything.
...Also, for the same thing you have:
NYCFC, Orlando, Minnesota, Cincinatti who has been horrific in their (at least) 1st year onwards.. NYCFC being the only one to make the playoffs and yet still not get too far after that.
MLS expansion model validation? Two out of 6. great numbers.
Don't forget that the league has changed the rules for expansion teams considerably between NYCFC/Orlando and ATL/LAFC with the later teams entering on more favorable terms. One could argue they made things a bit too favorable for ATL/LAFC based on how quickly both were able to rise to the top of the tables. Then again LAFC and Atlanta have both spent and spent wisely so the credit resides with them for maxing out their resources. Cincinnati and Minn have both shown that you can completely bungle the execution even when given the same favorable terms.