That certainly hasn’t always been true.
During the SFA era, I remember a comment being made where they admitted that they intentionally aimed to make Akuma strong in the game due to his story power level, just as the intentionally aimed to make Dan weak in the game due to his story power level.
That was an era when many players openly argued against attempts to balance fighting games. There was a false belief that attempting to balance a game would make it less interesting, that the only meaningful balance required making everyone identical. People, particularly those that favored high-mid or above tier characters, argued in favor of having a number of low tier characters for players who “wanted a challenge”. (At the same time, people that played low tier characters were often viewed negatively for not “playing to win”.)
Others sided with Capcom’s “story power levels”, or took it to greater extremes. Particularly when it gave them excuses to call for any characters they didn’t like to be shoved down the list.
There was also a belief that it only mattered if all your match ups evened out. A character that only had 3-7 and 7-3 match ups was considered to be as balanced as a character that had only 5-5 match up.