Originally Posted by
Oberon
To be fair some of this began in the several years before Byrne took over.
Around # 159, Reed put an amplifying head band on Sue to massively increase her powers. The effects were later said to have enhanced her permanently.
Later, # 170 or in between, George Pererz took over and really increased her abilities, visually (I know there was another writer, Wolfman?) but there were scenes showing Sue explaining how she could bi-focus on more than one thing with the FFs.
Another is around the early # 200s with the Xandar/Sphinx adventure (one of my favorites!) but the aging ray (and this was a story John B drew but I think Wolfman wrote) 's reversal decreased the ages of 3 of the FF, with it said Sue being younger than Reed and Ben may have tweaked back even more. Since that time, maybe slightly before Sue's portrayal's with the powers or other invisible things slowly improved.
But yes, John Byrne totally took it beyond and it has since, more or less, many mundane/type articles would indicate that she may be the most powerful member.