A large complicated well maintained and widely used library is infinitely preferable to a large complicated library you need to maintain yourself and used only by you. In a similar vein, a well known standard format (or encoding) will always be a better choice than some ad-hoc format you create yourself because not only will that standard have encountered and dealt with problems you haven't even considered, but there are also likely to be a plethora of libraries, frameworks, and tools that support that format, where as if you create something yourself you end up needing to create anything you need.
Your time is generally better spent working on solving your core problem rather than the dozens of ancillary problems that end up needing to be solved along the way (particularly where a whole bunch of other people have spent a whole bunch of time already solving those problems).
Your time is generally better spent working on solving your core problem rather than the dozens of ancillary problems that end up needing to be solved along the way (particularly where a whole bunch of other people have spent a whole bunch of time already solving those problems).