There are licenses known for excessive attribution requirements: in a single project the old four-clause BSD license required including 75 different texts in all advertising materials. The license text itself can be long (GNU FDL 1.3 takes more than 3 500 words, the Web browser that I use would spend nine A4 pages to print it): imagine an award pin with an FDL-licensed image or several pages long document derived from a GNU manual. Both need to include the GNU FDL text. It makes the license, despite being free (possibly in specific cases for FDL; in all cases for GNU GPL), unusable for some kinds of free works.
If you don’t consider award pins sufficiently complex and original, imagine a postcard from a traveling family member. It should have a beautiful photo on one side, like the ones that Wikimedia Commons has, and the whole other side filled by a letter describing their holidays, and your postal address. There is no place to fit nine pages of license text there, and the postcard is distributed by itself, so no separate booklet with required legal texts can be included.
It’s one of the reason for GNU FDL being used for ‘professional’ photos: it’s free, so it is accepted in free culture projects like Wikimedia Commons, but it's unusable so proprietary relicensing businesses work. Wikimedia Commons now discourages using GNU FDL for photos without dual-licensing under a more usable license.
I do believe that this is a significant bug in the license: copyleft licenses should be designed to not support proprietary relicensing or proprietary extensions businesses (i.e. proprietary software businesses) and should not have features that are useful nearly only for such businesses (while FDL has several, possibly since the license was designed to be used by traditional publishers). (There are several different problems in other, more important, copyleft licenses like GNU AGPL or GNU GPL3, e.g. the optional attribution requirement. Some of them are solved in copyleft-next; e.g. the Nullification of Copyleft/Proprietary Dual Licensing clause protects against proprietary relicensing by removing the copyleft for all in some cases.)
How can we solve this problem? By not distributing FDL-licensed works and by not recommending the use of such licenses for cultural works. This requires recommending specific better licenses.
GNU recommends their
for short documents like
README files. Unless the work is a part of
a GNU package, a free Creative Commons license is probably a better
solution: copyleft (without source provision requirement)
permissive CC-BY or
‘public domain but legal everywhere’
CC0. In its
clause 3(a)(1)(C), CC-BY-SA 4.0 requires to
indicate the Licensed Material is licensed under this Public License, and include the text of, or the URI or hyperlink to, this Public License,
so it’s sufficient to fit an URI like
https://creativecommons.org/licenses/by-sa/4.0/. (I have seen a
much longer text than this URI written on a single pea seed in
a local museum,
so this surely works for bigger works like award pins or postcards.)
A more general term is used in copyleft-next: ‘inform recipients how
they can obtain a copy of this License’ which is obviously satisfied
by an URI. (The whole officially recommended license notice is:
‘Licensed under copyleft-next version 0.3.0. See
for more information’. Compare the three paragraphs
recommended for the GNU GPL.)
This couldn’t have been done several decades ago. There was no Web in 1991 when GNU GPL2 was released (this is why usual GPL legal notices had an FSF address, changed several times after the license was released, until the GPL3 with both an URL and distributed license copy). It was reasonable to assume that the user couldn’t have obtained the license text from the Web, but now it’s probable that every computer user can access the Web, although not necessarily from their home. (How many GPL software recipients can access postal mail to use the source offers and not the Web?)
(This is not the only problem with long licenses or requiring to include their text in the work. It is a bigger problem that some licenses are too complex or too badly written to be understood by users, but that problem cannot be as easily quantified as their texts not fitting in the work: understanding of licenses is ‘cached’ in memories of their readers who have already met e.g. the GNU GPL3 for many other works. It would be also possible, and evil, to write a very short and incomprehensible license.)