it was one of those over exaggerations kubo and other authors do to build suspense and incase you didnt notice she was wrong, it was urahara who beat aizen with his sealing kido, sure he needed a bit of help from ichigo to activate it but he was undeniably the one who sealed and beat aizen. and what the hell are you on about? yamamoto could beat aizens shikai because he was strong? no just no. the key thing when fighting aizens shikai is intelligence we saw where not being smart got you when the other captains when they fought aizen. Yamamoto would have been able to beat aizen because of his strength and intelligence, if your just strong but gonna be fighting illusions to fight aizens shikai you need to be smart and take chances like how yamamoto let aizen impale him, which let him nearly beat aizen. so going of this you can probably see that urahara is probably one of the best people to fight aizens shikai as he is both smart and strong something key to fighting aizen. but ill say it again im not going any further as we are going into speculation which will get us no where.
also have you finally accepted that urahara beat byakuya mid to low diff?