Some people seems to think that "this is just what Ian thinks and his opinions, they aren't absolute in the series", although this is right, it's also more nuanced.
It's true that other official material not written by Ian features Sonic with a much higher level, but that still is much more limited in consistency.
The truth is that although it's canonical moments when Sonic is strong in works not written by Ian, the moments that feature Sonic at the level that Ian says they are are also canonical.
The more stories are written by Ian, the more "Ian's vision" becomes the most consistent one even if other depictions of the character are still canon.
Places like here, VsB Wiki, that focuses in "most consistent showings" of the characters, so if one day someone wants to show that even hypersonic speed aren't consistent with the series due to the huge number of comics written by Ian, that person wouldn't be wrong because the number of stories or official material depicting Sonic at far lower speeds far outnumbered the ones that showcase Sonic at high speed levels. The same in regards to attack speed or even durability.
So, yes, Ian's vision of the series are just his, but they are still the most consistent view of the series because by nature as a monthly comic series with various side-stories are going to have more content than the game side that had years without even a spin-off title.
It does not matter that "there's a stronger vision of the character" if no stories featuring that exist. Ian and the other IDW staff still are the ones pushing for stories to be made, so the stories are going to reflect their view of the series.
All that SEGA does is check the content and see if there are any lore and character contradictions, they do not push for storylines (At best they request some stuff like Warp Topaz not being explicitly destroyed), this is what the writers do. If no one pushes for high-level Sonic, then lower-level one is going to be the most consistent and well-known one.
And to be sure, no one here is going to get multiple keys for "Ian' vision" and "Kishimoto's vision" to take care of how different writers portray Sonic, even DC here is having a hard time trying to make consistent keys over different writers views.