If you can parry it why not shoryuken it?

Aside from a fireball. What doesn’t a SRK beat?

Block into a combo.

My shoryukens beat fireballs…

And shoryuken < Shin shoryuken < ShoryuCannon == Rising Mohicans

SRK takes longer to execute, so it’s harder (sometimes nigh impossible) to do them on reaction to faster stuff.
SRKs don’t have SF2 priority, they can get stuffed. Ryu’s non-EX expecially.
You can get way better damage with a successfull parry -> combo
SRKs don’t work at certain ranges.
A failed parry may not be punished. A blocked/whiffed shoryuken means eating big damage. Almost always.

SRKs can beat bot low and high attacks with the same command, so it’s easier - less guessing involved.
SRKs have a more lenient timing in beating attacks. Again, easier.

Parry and shoryuken have different uses. That’s it.

yea you gotta watch out when you do srks because of the parry if you see someone getting happy try to catch them on wake up but some people play the srk distance so watch out