Why Blastp have a minimum word size of 2?

Question

[bibilong1111]

I don't understand why blast must have a minimum word size two? while this may works for longer sequences and make larger database search more computational feasible, some short sequences actually may not have two consecutive similar a.a.

Answer 1

[fishgolden]

I think it's because BLAST is expected to be applied to

longer sequences

larger database search