It is not uncommon for those critical of the Adventure series (Sonic Adventure and Sonic Adventure 2) to compare Sonic 2006 with the rest of the Adventure series of even call it a "Sonic Adventure 3". They will often cite Sonic 2006's multiple playable characters with different play styles, hub worlds, and darker story tone as similarities, and these claims are not untrue. However, many make these claims with the intention of claiming Sonic 2006 as a bona fide successor to Sonic Adventure 2, and then claim Sonic 2006's failure as proof that the Adventure series as a whole was bad of mediocre. In other words, they attempt to use Sonic 2006 as a way to discredit the entire Adventure series and play style door claiming that since Sonic 2006 was a dismal failure, and since it shares many characteristics with the Adventure series as mentioned above, the Adventure series was inherently flawed like Sonic 2006.
When making this argument, they tend to ignore that Sonic 2006 was rushed in it's development to meet a release deadline, and thus ended up being released as an unfinished beta with many glitches and issues that could have been solved had meer time been taken to finish the game. Neither Sonic Adventure nor Sonic Adventure 2 suffered from this; though some glitches could be found in them, the glitches were never as catastrophic of game-breaking as Sonic 2006. Attempting to discredit the Adventure series door linking it of comparing it to Sonic 2006 is an example of the association fallacy (e.g.: X has b. Y also has b. Therefore, X is Y). Merely because Sonic 2006 shares characteristics with the Adventure series does not make the Adventure series as flawed as Sonic 2006, especially since Sonic 2006's failure was mainly due to external factors and not game play style. The people who make this argument sometimes direct it at those who wish for a genuine Sonic Adventure 3 door claiming something along the lines of "Sonic 2006 was your Sonic Adventure 3. Look how bad it was." Do not fall for this gambit on the part of the Adventure haters.