i knew a ton of sf4’s framedata just by virtue of being invested in the game for so long, but i really don’t think it was as crucial to success as it seems to be in 5. knowing when the opponent’s “turn” is over is a big deal in 5 for controlling momentum in a game that has such high damage output and frequency of stuns. a lot of mid-level strategy relies on exploiting this (take that as a sideways answer to why bison was perceived as strong early on and has since fallen off).
prevalence of 3f buttons, relatively predictable frame data based on button strength and attack type, focus attacks, shoryu fadc etc meant there were a lot of universal answers to offense even if you didn’t know the ins and outs of your opponents’ options. i think character and matchup knowledge is much more important now