Size alone does not a bureaucracy make, though it always helps (or hurts, looking at it from a rational perspective). Rules exist in the first place to benefit the group and its production. A bureaucrat is someone who has forgotten that simple fact, and worships the rules as ends in themselves, rather than means to getting the job done. This is one reason large organizations are more bureaucratic than smaller ones, the distance of most workers from the actual job.
The ultimate in rule-bound work is automated work.
A Web example:
On September 30 I was reading a well-established post on a web site I generally like, that already had lots of comments. Since it has a [reply] button, I naturally replied to comments that warranted it. I didn't even realize how many I had posted until I had gone back to the homepage and found I had 9 of the top 10 comments. I knew from a discussion a year before that the site owners "would prefer" people not post more than 3 of the latest 10 comments - but that was before one of them left and before the reply button, so I didn't know if it would be a problem, and it really didn't even occur to me as I was replying to those comments.
Apparently it did. On October 11, I tried to comment on a new post, my first comment since the 30th, and got an error page with "You are posting comments too quickly. Slow down." Outstanding stupidity on the part of the web site. What an outstandingly stupid contradiction between the site's name and action.