Yabia, the taimanim are not sefardi at all.
There were some sefardi gedolim after the inquisition, no doubt. And thsy were no less than their Ashkenazi counterparts. But in sheer number, the amount of Torah centers was less, the population was less, and they simply didn’t produce generations the likes of the shach and taz, reb akiva aigers, vilna gaons, noda beyehudas, etc…the hamon am also weren’t as educated towards the end, before the war. Ashkenazim were more successful in maintaining high standards of torah than sefardim. Rav ovadia changed that, and wanted to restore the pride of the Sefardim, who had fallen into a complacency of Sub -par education, which was replete with chunash, kabalah and sipurei tzadikim, but didn’t stress becoming talmidei chachamim.