No and yes. No, there's no rule to say one is too long. The more good information, the better, however, if a page is too long you sometimes might not get as many readers or comments as you might want because internet readers tend to have a short attention span.
Now don't think I know everything - you might write the most exciting page on a topic there could be. I've only found that some of my longest pages don't get enough traffic for them to have been worth all the effort I put into them, but other persons don't feel that way at all, or I guess, have had better results than me. I don't go much over 4 thousand words any more, and usually don't go over 2 thousand at all now.