I'm guessing it depends on two factors:

1: Do you have a team of twenty characters in your squad that you like? (And mostly 5* or 6*?)

2: Are you willing to pay any 'real money' whatsoever (even if only a limited amount compared to the true 'whales') for one-time gachas or daily deals that guarantee you 5* or 6*s?

If the answer to both those questions is "Yes" I can definitely see the logic behind preferring FGs for anything but 11-pulls as you're relying on other sources to get the characters you want for your team, and your team's already strong enough without needing extra characters to fill out your ranks.