Traditionally, the phrase too long; didn't read (abbreviated tl;dr or simply tldr) has been used on the Internet as a reply to an excessively long statement. It indicates that the reader did not actually read the statement due to its undue length. This essay especially considers the term as used in Wikipedia discussions, and examines methods of fixing the problem when found in article content.
As a label, it is sometimes used as a tactic to thwart the kinds of discussion which are essential in collaborative editing. On the other hand, tl;dr may represent a shorthand acknowledgement of time saved by skimming over or skipping repetitive or poorly written material. Thus, the implication of the symbol can range from a brilliant and informative disquisition being given up due to a reader's lack of endurance, interest, or intelligence, to a clustered composition of such utter failure to communicate that it has left the capable reader with a headache; judging this range is very subjective.
Many people who edit Wikipedia do so because they enjoy writing. However, that passion for writing can influence what they write to be longer than necessary. Sometimes this is because the writer incorrectly believes that long sentences and big words will make them appear learned. In other cases, misplaced pride prevents the author from seeing that not every word in their golden prose is necessary. Perhaps the author may be too hurried (or lazy) to write clearly and concisely; recall Pascal's famous quote, "I made this so long because I did not have time to make it shorter." While a genius like Pascal may have been justified in that balancing of priorities (just as neurosurgeons may not spend time doing the hospital landscaping), the rest of us must do our share of the work. In a related vein, administrator candidates may be judged merely by how much they have written, versus the much more subjective value of their contributions. Sometimes, the writer is an academic, whose occupation requires obscure, pseudointellectual verbosity and genre-specific jargon to impress his peers and justify additional funding. They don't necessarily know how to turn it off on Wikipedia, or even that they should.
Due to these factors, many articles, instructions and especially comments on Wikipedia are longer than necessary. Some of Wikipedia's core policies are considered by some to be too long (e.g. Creative Commons license). This may be considered to put too much burden on the readers to understand. Such problems can be seen elsewhere.
Writers often begin a project by writing long-winded drafts. As they go through the iterative process of revising their work, they (should) come to a better understanding of what they're trying to communicate and be able to reduce the length of the work. If this process is stopped prematurely, the result is needlessly long (as shown by Pascal's quote). Writers may err towards wordiness out of concern that short prose which is not carefully edited (at high time cost) would oversimplify, to the point of distorting or omitting, or carry a higher risk of being misunderstood.
Albert Einstein described the work of theorists as making theory as simple as possible, without failing to explain all empirical cases. His remark is often paraphrased as "everything should be made as simple as possible, but not simpler." Much argument between individuals results from one trying to point out the ways in which another's model of reality is incomplete. Thus the concept that Einstein mentioned may spur lengthy exposition, often to account for the corner cases.
A venerable aphorism is that "brevity is the soul of wit." A