Old masonry, why bundled in plugin?

I noticed some small problems in this plugin – First of all, the plugin bundles its own Masonry js, doesn’t include the Masonry that is now included in WordPress. Second, it includes Masonry 3.2.2 and looks like the latest is 3.3.2. Just wondering why this is set like this? Thanks.

https://wordpress.org/plugins/photoswipe-masonry/