Since you all want proof, here it is:
http://www.otakurevu.com/images/allaboutcapcom.jpg
THis is the cover for the "All about Capcom Fighting Mook"
THis Book is from Capcom, and was made to state all official information regarding Fighting games such as Street Figher.
You can view the translated version in http://kattuggla.oru.se/dmd01/dm0103/test/faqs/SFplotguide40.txt
According to the mook, The champion of the Street Fighter 2 tournament has also never been stated. Contrary to what some people think, there is no evidence or official statement whatsoever that Ryu won it, regardless of his popularity.
Basically, the winner of thournament is between Guile and Chunli. Storyline-wise, Chun-Li is the only character
with any shred of evidence whatsoever that she could have won it. Urien remarks in Street Fighter 3 that she was legendary during the second Street Fighter tournament, and what better way to become legendary than by winning the Street Fighter tournament?. Urien even said that she was the one who brought down “The Organization”, reffering to shadowloo.(strange how I repeat myself)
Logically-wise, Guile’s SF2 ending is the only one which really relies on him being the one to defeat M. Bison. Don’t get me wrong, Guile was’nt strong enough to beat him During Street Fighter alpha 3. But when the Psycho Drive was destroyed, Bison grew weaker, thus, allowing Guile to nail him.
But due to the new SF2 Revival endings, Chun-Li’s ending can happen without her defeating Bison in any way. she just states that she destroyed Shadaloo, not destroyed Bison.
If you’ve really read the plotguide like you claimed, then you should know that Guile DID beat bison, and Bison DID officialy invited competitros to the tournament.