Please use this thread:viewtopic.php?f=3&t=64985
But to answer your question, the majority of metalcore bands really aren't metal as defined by this site. They don't tend to have metal riffs, or very minimal metal riffs. On the contrary, such bands tend to be based more in -core characteristics than metal ones. A "profound influence" is not enough to get accepted; the music must be rooted in metal, not solely influenced by it. This may seem like an issue, at times, because we do have bands that may have started with an album that is clearly metal, and then devolved into simply being -core... or vice versa... given how we seek bands that have at least one predominantly metal album (and usually only require one metal album). It's for this reason that comparisons between bands, and trying to illicit why X band is accepted while Y band is not, makes a terrible argument for the site.
In this case, both Miss May I and August Burns Red are classic examples of metalcore that is rooted more in -core than in metal.