This is not about feelings, personal cost/benefit analysis of contributing. Contributors may just quietly disappear if you make them jump through too many hoops for no good reason. Again, this is just me, but if I had to edit my otherwise perfectly understandable text just to please a robot, I would abandon it unless I really care about the project.
I don’t think that enforcing consistency in this particular domain adds any value to documentation. Personally, I don’t care if the grammatical mood of docs is consistent for any software I use, as long as the meaning is clear. I might even prefer a slight variety in the style of docs, within bounds, as it may be less dry to read.
But note that I am the kind of person who finds it entertaining to read a monograph written about a subject by a bunch of different authors, and relish their various perspectives and styles.