Although |I can't claim to have read all the other Gospels in total, I think that they are very enlightening. To imagine that in c. 200 years only 4 gospel documents were written strikes me as highly implausible, and as we know that is not the case.

Then when one considers when the Bible was made canonical (more hundreds of years afterwards) it quickly becomes evident that it was early church politics rather than any other factor that is in play.