Because it is a budren to maintain and LGPL 2.1 does not require
them, but only suggest them:
> To apply these terms, attach the following notices to the library.
> It is **safest** to attach them to the start of each source file
> to most effectively convey the exclusion of warranty; and each
> file **should** have at least the "copyright" line and a pointer
> to where the full notice is found.
https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html#SEC4
Adrien Crivelli